Baker's Evangelical Dictionary of Biblical Theology 
Type of biblical literature that emphasizes the lifting of the veil between heaven and earth and the revelation of God and his plan for the world. Apocalyptic writings are marked by distinctive literary features, particularly prediction of future events and accounts of visionary experiences or journeys to heaven, often involving vivid symbolism. Later apocalypses often build upon and elaborate the symbolism employed by earlier ones. This is particularly the case in the Book of Revelation, in which not only earlier apocalypses but the whole Old Testament is plundered for ideas and symbols. Readers need to be alert to discern allusions.
It has often been argued that apocalyptic is a response to distress, enabling suffering people to see that God is in control of their circumstances and that ultimate deliverance is assured. There is certainly truth in this. However, as a total explanation it may be questioned. Apocalyptic is not the only biblical response to suffering, and therefore other factors must prompt it as well. Furthermore, the apocalyptic movement seems to have flourished also at times when particular suffering was not experienced. It is not clear, for instance, that Revelation is a response to suffering, although suffering is predicted in it (2:10; 13:10). Sociologically, it seems better to say that apocalyptic is the product of a prophetic movement, which claims to reveal the way things really are, both in heaven and on earth (the term "apocalypse, " the Greek name of the Book of Revelation, means "unveiling").
The biblical apocalyptic writings are characterized by certain distinctive theological ideas, which we will survey below. These concern particularly the relation between heaven and earth, the rule of God over both, and his ultimate victory over evil. However, these ideas are not found only in apocalyptic, but are themes of the whole biblical testimony in different ways. The mere appearance of these themes, therefore, cannot provide us with an adequate definition of apocalyptic. It is their appearance in this distinctive literary form, arising from this distinctive prophetic movement, which makes apocalyptic what it is.
The Bible contains two great examples of apocalyptic: Daniel and Revelation. But just as the distinctive themes of apocalyptic appear throughout the Scriptures, so we find that its literary forms have walk-on parts in many other books ( Ezekiel 1-3; Zechariah 1-6; Matthew 24; Ephesians 1:15-23; Hebrews 12:22-24 ). Extrabiblical apocalyptic works like 1Enoch (first century b.c. plus later additions) and 4Ezra and 2Baruch (both first century a.d.) are matched by apocalyptic passages in many other works. There was a flowering of apocalyptic in the late first century a.d., following the destruction of the temple and Jerusalem, as Jews sought revelation from God to explain that horrifying disaster. It is interesting that this is when the Book of Revelation is usually datedundoubtedly the greatest example of apocalyptic.
Within Judaism apocalyptic faded out, but an apocalyptic visionary tradition has remained alive within Christianity ever since. No subsequent work, however, ancient or modern, attains the grandeur and power of the canonical Book of Revelation.
Apocalyptic and Revelation The fundamental conviction of apocalyptic is that the world may be understood, but only by revelation that enables understanding. The mode of revelation varies. Daniel usually receives visionary dreams in his sleep (2:19; 7:1), but he also has day-time visions (10:4-5) and is able to pass on words from God like a traditional prophet (5:25-28). John receives his revelation while "in the Spirit" ( Revelation 1:10 ), which seems in his case to indicate an out-of-body journey to heaven (4:1 something claimed in other apocalypses of the period).
Apocalyptic is distinguished from other forms of prophecy in that God himself rarely speaks. The revelation is communicated through angels or other heavenly figures. Both Daniel and Revelation are full of speech, but in both books the only occasion on which the voice of God is unequivocally heard is Revelation 21:5-8 , a passage all the more climactic because of this rarity. In both books a particular angel Acts as a guide and instructor ( Daniel 9:21; Revelation 17:1; 22:8 ).
One interesting difference between Revelation and all other apocalypses is the extent to which it leaves visions unexplained. The usual pattern, both in Daniel and in the extrabiblical apocalypses, is that a vision is followed by an explanation of the symbolism ( Daniel 7:15-27; Zechariah 1:7-21 ), rather like the instances in which a parable of Jesus is followed by an interpretation ( Matthew 13:24-30,36-43; Mark 4:1-20 ).
This is only occasionally the case in Revelation. In 7:13 a heavenly figure actually asks John for an explanation of what he has just seen (but then provides it for him). In most cases the visions are just related, so that the reader is challenged to provide the interpretation, as in the case of the majority of Jesus' parables. It is not by accident that each of the letters to the churches ends with the appeal associated with the parables: "He who has an ear, let him hear." Right interpretation demands spiritual capacity and insight.
The Interconnectedness of Heaven and Earth This follows as much from the mode of revelation as from the fact of it. John's entry into heaven is a token of the closeness of heaven to earth. Having entered it, he is able from that vantage-point to survey both heaven and earth and to see how, really, earth can only be understood when it is seen as one-half of a much greater reality. The same is true, though less clearly, in Daniel.
This interconnectedness is expressed in various ways. There are heavenly counterparts of earthly realities, like the "angels of the seven churches" ( Revelation 1:20 ), and the four living creatures by the throne ( Revelation 4:6 ), and the "son of man" of Daniel 7:13 , who to some extent represents God's people in heaven ( Daniel 7:18 ). Similarly there are earthly counterparts of heavenly realities, seen for instance in the ghastly pairing of the two women who are also cities in Revelation 17-21 : on the one hand the Great Whore, who enslaves the world by war and commerce, and on the other the Bride of Christ, who brings healing to the nations.
There is mutual penetration, expressed both by the presence of the risen Christ in and with his church ( Revelation 1-3 ), and also by the way in which earthly powers are seen as nurtured by the power of the beast ( Revelation 17 ). Life on earth is determined from heaven: Decrees are issued from the throne that affect the earth ( Revelation 16:1; cf. Daniel 7:26 ), and events in heaven have a radical effect on earth (such as the ejection of the defeated dragon from heaven, Revelation 12:9,12 ).
Although earth is the sphere of the dragon and the beast, yet heaven and earth are seen as a single organism. This appears vividly in the compelling vision of uNIVersal worship in Revelation 5 , where John sees (and hears) the worship spreading from the throne in concentric circles outward, from the living creatures to the twenty-four elders, then to the myriads of angels (v. 11), and finally to "every created thing in heaven and on earth and under the earth" (v. 13), with this final shout of praise echoed by an "Amen!" back at the center. At the end heaven and earth will be recreated together ( Revelation 21:1 ).
God's Rule over a Chaotic World The basic message of Daniel 2-5 is that "the Most High God is sovereign over the kingdoms of men and sets over them anyone he wishes" ( Daniel 5:21 ). Similarly, but by very different means, the seals visions in Revelation 6 teach that the decree of God underlies all the chaotic horrors of human experience, including imperial conquest (6:2), war (6:3), violent and premature death (6:7), and the supreme (inexplicable?) injustice of being murdered for loyalty to the Creator (6:9-11).
As in the Book of Job, no reason is given for the presence of such things in God's world, but a profound answer is provided nonetheless: All these things issue from the scroll that only the slain Lamb is worthy to open (5:1-10). Such evils are permitted to exist in the world only because the LambGod himself in Christhas suffered them all firsthand (especially the final one).
Ultimately, God's rule over the world is to be expressed by the overthrow of the powers that produce such evils ( Revelation 6:15-17; foreshadowing the climactic overthrow of Babylon the Great in chapters 17-19 ).
The Protection of God's People The presentation of the "son of man" before God assures the status and security of "the people of the Most High" ( Daniel 7:13,22 ). This does not mean that they are preserved from suffering. The great beast, whose power Daniel sees being transferred to the "son of man, " will still wage war on the saints and prevail over them (7:21,25). But because the vision has been given in which the power of the beast has already been destroyed, God's people can be assured that they will be kept safe under its rule.
In Revelation the same idea is conveyed immediately by the vision of the risen Christ patrolling among the lampstands that represent the seven churches (1:20), and by his direct messages of warning and encouragement. He holds their "angels" in his hand. This is also the function of the dramatic interludes that intrude into the structural pattern of repeated "sevens." Between the sixth and seventh seals, John witnesses the "sealing" (play on words) of "the servants of our God" (7:3), so that they will not be harmed by the calamities he has just seen. A mark of ownership is set upon them, not to save them from the experience of war, famine, and disease, but to ensure that they will be among those who "come out of the great tribulation" (7:14), and who will no longer hunger or thirst (7:16).
Similarly between the sixth and seventh trumpets another interlude occurs ( Revelation 10:8-11:13 ) that concerns the preaching of the gospel before a hostile world. While they give their testimony, the two witnesses are kept safe, even though they are defeated by "the beast from the abyss" and follow their Lord through death and resurrection (11:5-12).
The message of the book is that, even though we cannot avoid bearing the mark of the beast as inhabitants of this world-order (13:16), yet, viewed from heaven, we also bear the name of God and of the Lamb on our foreheads, and are secure with him (14:1-5).
The Ultimate Victory of God . This is the theme that unites the biblical apocalypses with all others of the same period. The powers of this world will be overthrown and replaced by the kingdom of God. This means both secular world powers and the power of evil that lie behind them. The vision that energizes apocalyptic is the day when "the kingdom of the world has become the kingdom of our Lord and of his Christ" ( Revelation 11:15 ).
See also Theology Of Revelation
Bibliography . J. Bloch, On the Apocalyptic in Judaism ; F. C. Burkitt, Jewish and Christian Apocalypses ; R. H. Charles, The Book of Enoch ; idem, Testaments of the Twelve Patriarchs ; S. B. Frost, Old Testament Apocalyptic ; D. Guthrie, The Relevance of John's Apocalypse ; J. R. Harris, The Odes ; idem, Psalms of Solomon ; P. S. Minear, New Testament Apocalyptic ; F. C. Porter, The Message of the Apocalyptical Writers ; C. Rowland, The Open Heaven: A Study of Apocalyptic in Judaism and Early Christianity ; H. H. Rowley, Jewish Apocalyptic and the Dead Sea Scrolls ; idem, The Relevance of Apocalyptic ; D. S. Russell, The Method and Message of Jewish Apocalyptic ; L. L. Thompson, The Book of Revelation .
Holman Bible Dictionary 
Old Testament While portions of Joel, Amos, Zechariah, and Isaiah have apocalyptic features, Daniel is the only Old Testament book which is wholly apocalyptic.
New Testament “Apocalyptic” is derived from the Greek verb apokalupto , “to uncover,” and so figuratively “to disclose, reveal.” Its use, however, is due to the opening word of the Book of Revelation, apokalupsis , which means an “uncovering,” “a disclosure, a revelation.” This term has passed into English as “apocalypse.” When writers refer to “ the Apocalypse,” they mean the Book of Revelation; when they speak of an apocalypse, or apocalypses, or apocalyptic writings, they mean works written in a similar style to the Book of Revelation. The first sentence of the Book of Revelation is noteworthy in this connection: “The Revelation of Jesus Christ , which God gave to him , to shew unto his servants things which must shortly come to pass ; and he sent and signified it by his angel unto his servant John : who bare record of all things that he saw .” The italicized expressions illustrate the fundamental features of the genre of apocalyptic: these writings claim to originate from God ; they most frequently tell of a divine intervention soon to take place; their authors often use sign language—i.e. they “sign-ify,” employing pictorial language which is also parabolic; an angelic intermediary commonly explains to the prophet the meaning of the message conveyed to him; and the prophet makes known to others his visions (“all that he saw”). John's “apocalypse” is specifically stated to be a Christian revelation: it is “the revelation of Jesus Christ ,” received from God; accordingly it is described as “the Word of God and the testimony of Jesus Christ.” It is thereby declared to be an authentic apocalypse. John the prophet would have been aware that there were many other works which possessed similar literary characteristics as his own, the most notable being the Book of Daniel.
Extra-biblical Sources The other apocalyptic writings are outside the Bible and mainly belong to the period 200 B.C.-A.D. 100. The best known of the extra-biblical apocalyptic books are 1Enoch (often called “Ethiopic Enoch,” since it survives in that language), 2Enoch, 4Ezra, and 2Baruch. With these Jubilees, Psalms of Solomon, Testaments of the Twelve Patriarchs, and the Sibylline Oracles are generally classed, although their form differs from that of “classic apocalyptic.” It is not clear, however, that we should postulate a standard structure of apocalyptic writing; the use of symbolism, whether of animals or of mythical monsters, of visions and of messianic woes varies greatly. Various forms are used to convey the apocalyptic message. For example, the Testaments of the Twelve Patriarchs take the form of testaments, but poetic composition appears in the Sybilline Oracles. The most complete collection of Jewish and Christian apocalypses ever assembled is in the two volumes, The Old Testament Pseudepigraphs, edited by J. H. Charlesworth (New York, 1983,1985).
Apocalyptic Movement The so-called “apocalyptic movement” which gave birth to the apocalyptic literature had its roots in Israel's history. The creation myths of the Semitic world supplied quarries for the picture language employed by the prophets and apocalyptists. The leading literary features and apocalyptic message were conditioned above all by Israel's history and experience of God. Historical alienation created the conditions wherein apocalypticism flourished. Estrangement resulted from the disintegration of society, caused by oppression or the ravages of war. The isolation of a group within its society also caused alienation. While the Jewish literature that concerns us was the offspring of Old Testament prophecy, the apocalyptic movement had parallels in the contemporary world of the Middle East. Other nations resisted Greek rule and created hopes of a renewal of a native kingship. They divided history into four successive kingdoms and expected a god to intervene to restore order and bring victory. This shows the links between the religious thought of nations of the ancient world, of their response to aggressive oppression, and of their hope in deliverance from God.
Characteristics of Apocalyptic Writing The characteristics of Jewish apocalyptic writings are widely discussed, sometimes without due regard for the diversity in these writings. It is commonly agreed that three major features characterize apocalyptic thinking: dualism, determinism, and pessimism. Dualism is the dominant characteristic and is expressed in two ways: (1) in a dual spacial order—powers of heaven and powers of hell, hence angels and demons in abundance, spirits of good and spirits of evil, a holy Spirit and an evil prince of this world; (2) in a historical dualism—the present age is ruled by the evil powers and is wholly wicked, but it will be succeeded by the age to come, which will be ruled by God and therefore will be good. The ordering of the ages for the accomplishment of God's purpose in the coming age often entails a determinism, which can be applied to the last detail of history. This means God has already planned each historical event regardless of human choices and acts. This in turn can lead to pessimism, such as that in 4Ezra. Examples of dualism or determinism in some literature does not mean every writer of apocalyptic works believed in a world dominated by dualism and determinism. Persian religion had the ultimate dualism. The powers of good and evil were co-equal. This was impossible in Jewish thought, whose main belief was one God without equal. The idea that the devil is lord of the present age was not shared by all apocalyptists; for example, in Daniel 4:25 , Nebuchadnezzar was told that he would be humbled until he learned that “the most High ruleth in the kingdom of men, and giveth it to whomsoever he will,” (compare Revelation 13:5-10 ). Positively, we should view these insights as subsumed under the heading of the sovereignty of God. He is Lord of the universe, and so of all powers; the good are His ministers, the evil have to contribute to His will. The two ages are a clarification of the prophetic view of history leading to the day of the Lord, the coming of God, and the fulfillment of His purpose in the victorious kingdom of God. The determinism of which these writings speak is an attempt to set forth God's will as done on earth as in heaven. Such a faith is not rightly described as pessimism. It certainly postulates the inability of humanity to save itself and thus looks to God to complete history in the kingdom of glory. The end therefore is good !
Most apocalyptic works are ascribed to an ancient saint, as their names imply (for example, the books of Enoch , the Apocalypse of Abraham , of Noah , of Ezra , of Baruch ). The reason for this form is still uncertain; it obviously includes the desire for a book to gain a hearing, but it also expresses the conviction that the revelations have come down from ancient times, somewhat as the Pharisees believed that their tradition went back to Moses. Pseudonymity, however, was not a necessary adjunct of apocalyptic work; the literature of Qumran is without it, and the supreme example of apocalyptic writing, the Book of Revelation, was issued in the name of its author.
Significance The chief importance of the apocalyptic literature was its enabling the prophetic faith in God and hope for His kingdom to burn brightly in oppressive times. At its best it was more than maintenance of dogma. It encouraged people to be ready for and participate in God's final victory in history. Thus it encouraged an alienated, estranged, defeated people to live for God and to hope in His promised coming. Apocalyptic writing found its correction and true fulfillment in the message of Jesus, and in His living, dying, rising, and the hope of His appearance.
Webster's Dictionary 
(1): (n.) Alt. of Apocalyptist
(2): (a.) Alt. of Apocalyptical