Hastings' Dictionary of the New Testament 
Separation —In discourses descriptive of the present condition and future prospects of the Kingdom of God, Christ taught that the Kingdom in its ideal state of purity would not be realized till the end of the world, when the object in view is to be attained by means of a judicial separation between real members and those who are members only in outward appearance or profession ( Matthew 13:24-30; Matthew 13:36-43; Matthew 13:47-50). In opposition to prevailing ideas on the subject, Christ plainly indicated that the Kingdom of God, throughout the course of its earthly development, must contain conflicting elements of good and evil, and gravely deprecated any premature attempt at separating them. The intermixture foreshadowed was not a pure kingdom existing amid a corrupt environment, but a kingdom itself invaded and pervaded to some extent by a corrupt element.
Wendt maintains that Christ did not ‘contemplate an outward separation of His disciples from the fellowship of the Israelitish nation and religion’ ( Teaching , ii. 351 f.); and that the parables of the Tares and the Drag Net were intended to guard against any attempt in that direction. But the evil element referred to in the parables is not that which has always existed in the world, and must be expected to continue, but that which has entered the Kingdom in the course of, and as the result of, its own operations, which tend to gather within its pale spurious adherents as well as genuine ( Matthew 13:47). A separation, moreover, from the Jewish Church, as Christ must have foreseen, was imminent and inevitable, if for no other reason, because the spirit and aims of the society founded by Him were so widely different ( Matthew 9:16 f.), and it is clearly implied in the announcement of the approaching downfall of the Jewish State ( Luke 19:43 f.).
Serious objection must also be taken to the view, which has often been advocated, in the interests of a pure Church, since the Donatist controversy in the beginning of the 5th cent., that the evil element is in the world, the good element in the Kingdom, and the blending of the two merely contiguity or co-existence in space. It is hard to see why our Lord should have been at such pains to point out what must be perfectly obvious to everybody, that the world is evil, and why He should recommend a tolerant attitude toward the evil, instead of making it a reason for earnest evangelistic effort. Such a condition of things had long existed, and was only what might be expected. It could by no possibility give rise to the painful reflexion and inquiry described in the parable ( Matthew 13:27, which are in reality due to the circumstance that the sin which exists in the world ‘is always forcing its way anew into the circle in which the Kingdom of God is being realized.’ The surprise and disappointment expressed by the servants are occasioned by the emergence of a phenomenon wholly unexpected, when the field originally sown with good seed is found afterwards to contain tares—an alien and unwelcome addition; and their impatient zeal to begin at once the work of purification is, in the circumstances, extremely natural. It is almost needless to remark that if the Son of Man at the end of the world is to ‘gather out of his kingdom all things that offend (πάντα τὰ σκάνδαλα), and them which do iniquity,’ they must have existed previously within it ( Matthew 13:41).
The contrast is obviously between the mixed state of affairs now prevailing, and the Kingdom as it shall be, when, freed from all admixture, it shines forth in its pure native lustre ( Matthew 13:43). Meanwhile the disciples are directed to exercise a wise patience, and to refrain from drastic measures of reform which might result in injuries still more serious to the cause they have at heart ( Matthew 13:29). Their attitude of tolerance is by no means to be taken, however, as implying sanction or approval of existing abuses. Christ freely admitted that the presence and conduct of unworthy members were inconsistent with the Divine ideal of the Kingdom, and could not but prove injurious to its best interests ( Matthew 13:28; Matthew 13:39). But the possibility of admixture was unavoidable, in view of the fact that the Divine Kingdom welcomed all without distinction, on their professed compliance with the conditions of admission to its membership. The wide and sweeping character of its operations exposed it to the risk of gathering into its bosom some who might do it serious discredit in the eyes of those who had its purity and welfare at heart, as well as of the world at large ( Matthew 13:47).
It would be a mistake to suppose that Christ meant to withhold from His disciples authority to exercise discipline in the case of grave offences against the laws of the Kingdom, discipline which they did, in point of fact, afterwards exercise ( Acts 8:20-23, 1 Corinthians 5:3-5), but which had for its object the edification, and not the destruction, of believers ( 2 Corinthians 10:8). The infliction of censure or punishment in the case of gross offenders was intended to have a healing effect, and instead of aiming at permanent exclusion from religious fellowship and privileges, had ultimate restoration to these in view. What our Lord deprecates is any attempt to forestall the Final Judgment by the absolute separation of offenders from religious fellowship, a separation issuing only in destruction ( Matthew 13:40). Having regard to the imperfections that cleave to human nature while still in a state of probation, it is evidently His intention that lenity rather than severity should characterize the treatment of offenders, lest good and evil be rashly included in one common condemnation, and the remedy prove so violent as to be worse than the disease ( Matthew 13:29). Besides, the exercise of a decisive judgment would in many cases require a delicacy of discrimination and an insight into human character possessed only by a Divine person, and it is accordingly reserved for the Son of Man, in His capacity as Judge, at the end of the world. Even strong presumptive proof of moral unworthiness would not, in the case of mere human judgment, afford sufficient guarantee against the risk of mistake ( Matthew 13:29). See Church, Excommunication.
While the disciples are enjoined to preserve an attitude of patient endurance toward evil within the Kingdom, Christ held out to them the prospect of a day of final sifting in which it would be completely eliminated ( Matthew 13:30; Matthew Mat_13:48). The period of intermingling is at last to come to an end. The great separation to be then effected between the two elements so long opposed, has primarily in view the interest of an ideal purity, for which all earnest ones have anxiously hoped and striven. The burning of the tares does not refer so much to the fate which ultimately overtakes evildoers, as to the fact that they can no longer exert a depressing effect on the fortunes of the Kingdom. Hitherto they have existed as an obscuring medium, but with the removal of the scandals and their authors ( Matthew 13:41) the character of the righteous at last appears, without shadow of eclipse, in all its unsullied purity and splendour ( Matthew 13:43). The sifting out of unworthy members results in irreparable loss, at the same time leading, as it does, to their permanent exclusion from heavenly privileges ( Matthew 24:50, Matthew 25:11 f., Matthew 25:30). The grounds of separation are quite general, consisting in broad fundamental distinctions of moral character, not clearly apparent at the outset, but becoming increasingly manifest as time goes on ( Matthew 13:26), so that at last a division into two classes, the righteous and the wicked, becomes inevitable ( Matthew 13:41; Matthew 13:43; Matthew 13:49). Elsewhere the twofold classification is made to turn on characteristics of a more specific kind, such as confession or denial of Christ in times of peril ( Matthew 10:32 f.), faithful or unfaithful exercise of stewardship ( Matthew 24:45; Matthew 24:48), diligence and fidelity in the use of entrusted gifts, or failure to improve them due to unbelief and indolence ( Matthew 25:20; Matthew 25:22; Matthew 25:24 f.). Profession without practice ( Matthew 7:21-23), selfish ambition ( Matthew 18:1-3), an unforgiving disposition ( Matthew 18:34 f.), mark men out for exclusion from the perfected Kingdom; while childlike humility ( Matthew 18:3), lowly acts of service ( Luke 22:24-30), preparedness for all kinds of sacrifice up to that of life itself ( Matthew 16:25; Matthew 16:27; Matthew 19:27-29), are sure passports to participation in its benefits. See, further, artt. Eternal Punishment, Universalism.
Literature.—E. L. Hull, Serm . 2nd ser. 191; H. Bushnell, New Life , 306; B. F. Westcott, Peterborough Serm . 3; T. G. Selby, Unheeding God , 24; G. Body, Life of Love , 27.
W. S. Montgomery.
King James Dictionary 
SEPARA'TION, n. L. separatio.
1. The act of separating, severing or disconnecting disjunction as the separation of the soul from the body. 2. The state of being separate disunion disconection.
All the days of his separation he is holy to the lord. Numbers 6 .
3. The operation of disuniting or decomposing substances chimical analysis. 4. Divorce disunion of married persons.
Webster's Dictionary 
(1): ( n.) Chemical analysis.
(2): ( n.) Divorce.
(3): ( n.) The act of separating, or the state of being separated, or separate.
(4): ( n.) The operation of removing water from steam.
Holman Bible Dictionary 
Leviticus 12:2 12:5 Leviticus 15:20 15:25-26 Numbers 6:1 Numbers 19:1
International Standard Bible Encyclopedia 
sep - a - rā´shun : In the Pentateuch the word niddah specially points to a state of ceremonial uncleanness ( Leviticus 12:2 , Leviticus 12:5; Leviticus 15:20 ff; Numbers 6:4 ff; Numbers 12:13; Numbers 19:21 ). For a description of the "water of purification," used for cleansing what was ceremonially unclean (Nu 19), see Heifer , Red; Uncleanness . For "separation" in the sense of nēzer , see Nazirite .