From BiblePortal Wikipedia

Hastings' Dictionary of the New Testament [1]

The idea of unity is one of those that are most pervasive in the apostolic writings; and naturally so. Christianity is the religion of reconciliation; and, fully recognizing the radical character of the antagonisms that reveal themselves in experience, it everywhere discloses a profounder unity in which these opposites are harmonized. While it does not assume the function of a philosophy, it does claim to give, from the moral and teleological standpoint, a synthetic view, and, indeed, the only synthetic view, of reality; in Christ it finds the way, the truth, and the life by which the unity of God and man and the whole universe of being must be finally achieved.

On the cardinal issue, existence is seen both as a unity and as a duality. The duality is wholly and tragically real. Physical evil is no illusion, but is the correlate of moral evil; and moral evil is not an inevitable stage in the evolution of moral good, but is sin , that which absolutely ought not to be. Yet this duality exists within the circumference, so to say, of an eternal unity before and after; an original self-existent principle of evil is excluded by NT thought. On the other hand, it attempts no solution of the problem how duality has arisen out of pre-existent unity; it is content to trace sin back to the beginning of human history, or, if further, to the agency of a Tempter who had himself fallen from his first estate. Its interest in the problem is not at all speculative, but solely practical-to emphasize, on the one hand, the fact of man’s innate sinfulness, and, on the other, the fact that sin is precisely that which has no point of origination in the Divine causality, but is in essential antagonism to the nature and will of God.

1. The Being of God as the primal source of all unity. -( a ) As against all polytheistic or dualistic systems, apostolic thought posits this as its first truth ( 1 Corinthians 8:4;  1 Corinthians 8:6,  Ephesians 4:6,  James 2:19). And this ensures a unity in nature and history. Although the marks of imperfection and disorganization are everywhere seen upon the face of Creation, although it is in bondage to the law of decay and corruption, and is the scene of apparently fruitless tragedy ( Romans 8:20-22), yet it is pervaded by a unity of rational purpose and control ( Romans 8:28,  Acts 27:22-24); and this is true not only of natural processes and events, but of those that are brought about by the volition of men or other free agents ( Acts 2:23;  Acts 21:10-14,  2 Corinthians 12:7).

( b ) The Divine nature is ethically a unity-light in which there is no darkness at all. God is ‘faithful’ ( 1 John 1:9,  2 Timothy 2:13), unchangeably self-consistent ( James 1:17). His different modes of action upon different objects only prove the immutability of His moral nature ( Romans 2:6-10,  2 Thessalonians 1:6-7;  2 Peter 2:4-9). And the centre of this unity, from which all His ethical attributes derive, is Love; the ultimate explanation of all that God does, and purposes, and permits is-God is Love ( 1 John 4:8). Hence, also, the Righteousness of God, His Will as imperative for all beings capable of ethical life, is a unity. His Law is an ethical organism, expressing in every part the same principle ( Romans 13:8-10), to violate which in one point is virtually to violate the whole ( James 2:10). Hence, again, sin is a unity. Within all individual sins (ἁμαρτήματα) there lives that (ἡ ἁμαρτία) which makes them to be sinful. St. Paul almost personifies this principle of sin ( Romans 7:11;  Romans 7:14). St. John defines it as ἀνομία, lawlessness, the assertion of an evil egoistic will against the perfectly good will of God ( 1 John 3:4). Sin is not seen in its true character until it is seen in its unity.

2. Unity of mediation. -The explanation of the dualism we are conscious of in experience is not found, as in Gnosticism, in the transition from the transcendent God to the created universe. The unity of the Divine self-existence is not lost when related to other being; its fullness is not portioned out in successive separate emanations. There is one God, and one Mediator ( 1 Corinthians 8:6,  1 Timothy 2:5)-He who became in human history the ‘man Christ Jesus.’ In Him, as the Image and Only-begotten of the Father, the undivided fullness of the Godhead dwells ( John 1:14,  Colossians 2:9); and He is not only, by His Incarnation, the one Mediator to mankind of all Divine life, truth, and saving grace, but the Divine agent in all creation ( John 1:3,  Colossians 1:16), and the principle of its unity ( Colossians 1:17). See Fulness; Mediation.

3. The unity of man. -( a ) The generic unity, physical and moral, of mankind (already seen in the OT and in Stoicism) is a presupposition of Christian soteriology; human nature has everywhere the same spiritual capacities, needs the same salvation, and is capable of appropriating it by the same means ( Romans 1:16, etc.). This unity is categorically affirmed ( Acts 17:26); historically it has its source in descent from one common primal ancestor ( Romans 5:14-19,  1 Corinthians 15:22;  1 Corinthians 15:47), but ultimately in the fact that man as man is the image and offspring of God ( Acts 17:28-29).

( b ) Hence there is unity as regards responsibility. Apart from special revelation, man possesses a rational and moral nature, made for the knowledge and love of God, with capacities for discerning the self-manifestations of God in His creative and providential activities ( Acts 14:17,  Romans 1:19-21); and especially does conscience bear witness to the sovereign imperative of His righteousness ( Romans 2:14-15).

( c ) But, actually, unity in responsibility has become unity in sin. Human character has become corrupt at its hereditary source ( Romans 5:12;  Romans 5:17-19;  Romans 5:4 Ezr  Romans 3:26, Apoc. Bar . liv. 15, 19); human life universally characterized by wilful sin ( Romans 3:9-20), involving guilt ( Romans 3:19) and that separation from God ( Ephesians 4:18,  Colossians 1:21) which is death ( Romans 6:23,  Ephesians 2:1;  Ephesians 2:5,  Colossians 2:13).

4. Unity of redemption .-( a ) For the common human need one common redemption is provided ( Acts 4:12,  Romans 10:4;  Romans 10:12,  1 John 2:2), to be received by the same means ( Romans 4:11-16,  Galatians 2:16,  1 John 1:7-9), working to the same issues of forgiveness ( Romans 8:1,  Revelation 1:5), reconciliation to God ( Romans 5:1;  Romans 5:10,  2 Corinthians 5:18-21), enduement with the Spirit ( Romans 8:1-16), eternal life ( Romans 5:17;  Romans 5:21,  1 John 5:11;  1 John 5:13;  1 John 5:20). Possessing such fellowship with God in Christ, as the source of their common life and object of their common faith, Christians also possess a unique spiritual affinity and fellowship with each other. And, in the Apostolic Age, the consciousness of unity reaches its intensest point in the conception of this fellowship, alike Divine and human, as embodied in the Church. In this, racial and social distinctions-Jew and Gentile, bond and free-serve only to emphasize and enhance the fact that those who are united in Christ, however different in all else, have immeasurably more in common than those who are separated by Christ, however alike in every other respect ( 1 Corinthians 7:22,  Galatians 3:28,  Ephesians 2:11-22). So, also, distinctions of custom and even of conviction do not disappear ( Romans 14:5); yet even such diverse interpretations of truth and duty ought only to evoke a fuller realization of supreme truth and duty, the faith and love in which all are one. Unity is emphasized as against mere uniformity (1 Corinthians 12). In the spiritual body, as in the physical, a rich diversity of gift and function is necessary to the complete expression of the organic life-principle ( Romans 14:4-6). It is only in its complex collective unity that renewed humanity can reach its Divine ideal ( Ephesians 4:11-13).

( b ) But in the Pauline Epistles it is seen that, Christ being what He is, universal Mediator and Lord, He is destined to become by His reconciling work the centre of a unity that embraces all existence, and that is essential even for the full redemption of man. Christ must be Head over all things to His Body, which is the Church ( Ephesians 1:22); hostile elemental forces must be subdued ( 1 Corinthians 15:24,  Ephesians 1:21); all things, whether on earth or in heaven, must come under His reconciling sway ( Colossians 1:20), and the whole creation be emancipated into the liberty that belongs to the glorified state of God’s children ( Romans 8:21), that God may be all in all ( 1 Corinthians 15:28).

5. The final unity. -As has been said, the NT attempts no solution of the problem how duality has arisen out of an original unity, and the same is largely true of the converse problem, how the existent duality is to be finally overcome, resolved into the eternal unity of Divine truth and love. One thing only is seen as a certainty for Christian faith: of such unity Christ is the sole cause and ever-living centre. He must reign: it is unto Him that all things must be subdued; it is as the fruit of His sacrifice that God will reconcile all things unto Himself; it is in His name that every knee shall bow, Him that every tongue must confess as Lord, to the glory of God the Father. But in apostolic thought (which here virtually means Pauline) the age to come seems to be viewed in different perspectives. In the one the curtain falls upon an unresolved or, at any rate, imperfectly resolved dualism. Christ’s enemies are made His footstool; yet their subjection, if not merely physical, is not completely moral. Evil is still evil, though in chains and, to this extent, subject to the righteousness of God. This is the vision which arises when the final issue is viewed from the side of human freedom and responsibility. If absolute finality is not ascribed to the spiritual choices of the present, the future of those who in this present world reject the life-giving Spirit is left in unrelieved gloom. From another point of view, the necessary consummation of Christ’s victory is seen to be nothing less than the moral unification of all existence. The ruin wrought by Adam and the redemption wrought by Christ seem to be co-extensive in human history ( Romans 5:16,  1 Corinthians 15:22); and in the dispensation of the fullness of the times it is God’s purpose to bring all things again into unity (ἀνακεφαλαιώσασθαι) in Christ ( Ephesians 1:10; cf.  Colossians 1:19-20,  Philippians 2:9-11). When Christ’s work is done, God will be all in all ( 1 Corinthians 15:28). And this is the vision that arises when the final issue is regarded from the side of Divine sovereignty and purpose. As to the means by which such a consummation may be hereafter achieved the NT is silent. Again it has to be said that its interest in the problem is wholly practical, not speculative-to emphasize the fact that there is complete, eternal deliverance and blessedness for all who are Christ’s; that in some sense, at some time, by some means beyond our ken, Christ will be universally victorious, because God is God, and God is Love.

Robert Law.

Holman Bible Dictionary [2]

Old Testament Central to the faith of Israel is the confession of the unity of God: “Hear, O Israel: The Lord Your God is one Lord” ( Deuteronomy 6:4 ). Because God is one, one set of laws was to apply to both Israelites and foreigners ( Numbers 15:16 ). Human history is a story of sin's disruption of God's ordained unity. God's ideal for marriage is for husband and wife to experience unity of life, “one flesh” ( Genesis 2:24 ). Sin in the garden bred mistrust and accusation ( Genesis 3:12 ). Stubbornness of will (“hardness” of heart,  Mark 10:5 ) continues to disrupt God's desired unity in marriage. God's ideal for the larger human family is again unity. The primeval unity of humanity (“one language”  Genesis 11:1 ) was likewise disrupted as a result of sinful pride ( Genesis 11:4-8 ). The prophetic vision of God's future anticipates the day when God will reunite the divided kingdoms of Israel and Judah, bringing back all the scattered exiles ( Ezekiel 37:15-23 ). Indeed, the prophetic hope includes the reuniting of all the peoples of the world under the sovereignty of the one Lord ( Zechariah 14:9 ).

New Testament Jesus prayed that His disciples would experience unity modeled on the unity Jesus experienced with the Father ( John 17:11,lb21-23 ). Such unity verifies Jesus' God-sent mission and the Father's love for the world. Jesus' prayer for unity was realized in the life of the earliest church. The first believers were together in one place; they shared their possessions and were of one heart and soul ( Acts 2:1 ,Acts 2:1, 2:43;  Acts 4:32 ). As in the Old Testament, sin threatened the God-ordained unity. The selfishness of Ananias and Sapphira ( Acts 5:1-11 ), the prejudice of those who neglected the Greek-speaking widows ( Acts 6:1 ), the rigidness of those who demanded that Gentiles become Jews before becoming disciples ( Acts 15:1 )—all threatened the unity of the church. In every circumstance, however, the Holy Spirit led the church in working out creative solutions that challenged the church to go beyond dissension to ministry ( Acts 6:2-7;  Acts 15:6-35 ). Paul spoke repeatedly of believers as “one body in Christ” which transcends varieties of giftedness ( Romans 12:5-8; 1Corinthians 12:13, 1 Corinthians 12:27-30 ) and human labels ( Galatians 3:28;  Ephesians 2:14-15;  Ephesians 3:6 ). For Paul, the unity of the church reflects the unity of the Godhead: one God ( 1 Corinthians 12:6 ); one Lord ( Romans 10:12;  1 Corinthians 12:5;  Ephesians 4:5 ); and one Spirit (1Corinthians 12:4, 1 Corinthians 12:11; also  Acts 11:17 ). Christian unity has various aspects: the shared experience of Christ as Lord and confession of Christ in baptism ( Ephesians 4:5 ,Ephesians 4:5, 4:13 ); the shared sense of mission (“one mind,”  Philippians 2:2 ); the shared concern for one another ( 1 Corinthians 12:25; “same love,”  Philippians 2:2;  1 Peter 3:8 ); and the shared experience of suffering for Jesus' sake ( 2 Corinthians 1:6;  Philippians 1:29-30;  1 Thessalonians 2:14;  1 Peter 5:9 ).

Chris Church

King James Dictionary [3]

U'NITY, n. L. unitas.

1. The state of being one oneness. Unity may consist of a simple substance or existing being, as the soul but usually it consists in a close junction of particles or parts, constituting a body detached from other bodies. Unity is a thing undivided itself, but separate from ever other thing. 2.Concord conjunction as a unity of proofs. 3. Agreement uniformity as unity of doctrine unity of worship in a church. 4. In christian theology, oneness of sentiment, affection or behavior.

How good and how pleasant it is for brethren to dwell together in unity!  Psalms 133 .

5. In mathematics, the abstract expression for any unit whatsoever. The number 1 is unity, when it is not applied to any particular object but a unit, when it is so applied. 6. In poetry, the principle by which a uniform tenor of story and propriety of representation is preserved. In the drama, there are three unities the unity of action, that of time, and that of place. In the epic poem, the great and almost only unity is that of action. 7. In music, such a combination of parts as to constitute a whole, or a kind of symmetry of style and character. 8. In law, the properties of a joint estate are derived from its unity, which is fourfold unity of interest, unity of title, unity of time, and unity of possession in other words, joint-tenants have one and the same interest, accruing by one and the same conveyance, commencing at the same time, and held by one and the same undivided possession. 9. In law, unity of possession, is a joint possession of two rights by several titles, as when a man has a lease of land upon a certain rent, and afterwards buys the fee simple. This is a unity of possession, by which the lease is extinguished.

Unity of faith, is an equal belief of the same truths of God, and possession of the grace of faith in like form and degree.

Unity of spirit, is the oneness which subsists between Christ and his saints, by which the same spirit dwells in both, and both have the same disposition and aims and it is the oneness of christians among themselves, united under the same head, having the same spirit dwelling in them, and possessing the same graces, faith, love, hope, &c.

Webster's Dictionary [4]

(1): ( n.) In dramatic composition, one of the principles by which a uniform tenor of story and propriety of representation are preserved; conformity in a composition to these; in oratory, discourse, etc., the due subordination and reference of every part to the development of the leading idea or the eastablishment of the main proposition.

(2): ( n.) Such a combination of parts as to constitute a whole, or a kind of symmetry of style and character.

(3): ( n.) Any definite quantity, or aggregate of quantities or magnitudes taken as one, or for which 1 is made to stand in calculation; thus, in a table of natural sines, the radius of the circle is regarded as unity.

(4): ( n.) Concord; harmony; conjunction; agreement; uniformity; as, a unity of proofs; unity of doctrine.

(5): ( n.) The state of being one; oneness.

(6): ( n.) The peculiar characteristics of an estate held by several in joint tenancy.

Vine's Expository Dictionary of NT Words [5]

1: Ἑνότης (Strong'S #1775 — Noun Feminine — henotes — hen-ot'-ace )

from hen, the neuter of heis, "one," is used in  Ephesians 4:3,13 .

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [6]

as a philosophical term, signifies oneness. Aristotle makes it the element of number, and defines it as indivisibleness. In the Kantian philosophy it is defined as "that mental representation in the understanding by which the manifold is thought of as linked together." It is by the same authority classified as anatlytic, or unity of a logical connection; and synthetic, or unity of intentions in the concept of an object. As a theological term, unity is employed to signify a oneness whether of sentiment, affection, or behavior ( Psalms 133:1). The "unity of the faith" is an equal belief of the same great truths of God, and the possession of the grace of faith in a similar form and degree ( Ephesians 4:13). The "unity of the spirit" is that union between Christ and his saints by which the same divine spirit dwells in both, and they have the same disposition and aims; and that unity of the saints among themselves by which, being joined to the same head, and having the same spirit dwelling in them, they have the same graces of faith, hope, love, etc., and are rooted and grounded in the same doctrine of Christ, and bear a mutual affection to each other. When Christian unity is spoken of in the New. Test., it generally means the unity of dispensation for the various classes of converts. It is expressive of the great principle that all were to be under one fold and one Shepherd.

International Standard Bible Encyclopedia [7]

ū´ni - ti  :   Psalm 133:1 for ( יחד , yāḥadh , "unitedness," and  Ephesians 4:3 ,  Ephesians 4:13 for ἑνότης , henótēs "oneness." Also Sirach 25:1 the King James Version for ὁμόνοια , homónoia "concord" (so the Revised Version (British and American)).