The Doctrine of Separation and its Basis in the Doctrine of God.
In the Westminster Shorter Catechism Q4, “What is God?” The answer is “God is a spirit, infinite, eternal, and unchangeable, in his being, wisdom, power, holiness, justice, goodness, and truth.” Vincent defines the holiness of God as “his essential property, whereby he is infinitely pure; loveth and delighteth in his own purity, and in all the resemblances of it which any of his creatures have; and is perfectly free from all impurity, and hateth it wherever he seeth it” (Thomas Vincent, The Shorter Catechism of The Westminster Assembly Explained and Proved from Scripture [Edinburgh: The Banner of Truth, 1674], 31).
The Hebrew word for “holy,” or “holiness” is the word qadash or qodesh. The verb qadash “connotes the state of that which belongs to the sphere of the sacred” (TWOT, sv “qdsh,” by Thomas E McComiskey). The noun qodesh “connotes the concept of ‘holiness,’ ie, the essential nature of that which belongs to the sphere of the sacred and which is thus distinct from the common or profane” (Ibid). The etymology of the word is significant. Scholars have suggested that “the root qdsh is derived from an original bilateral qd (“cut”). ... The meaning ‘to separate’ is favored” (Ibid).
In the NT, the parallel words for qadash and qodesh are the Greek hagiazo and hagiasmos respectively. It signifies “separation to God” and “the conduct befitting those so separated” (Vine, Dictionary, 565) . The essential element of holiness is that of separation. Separation is intrinsic to the doctrine of holiness. We separate from all forms of unbelief and apostasy because it is God’s nature to separate from such. The God of the Bible is a God who is holy. Being holy, He demands the same from His people. God said in both the OT and NT, “Ye shall be holy, for I the LORD your God, am holy” (Lev 19:1, 1 Pet 1:16). Buswell said that our code of Christian conduct is, “ultimately derived from the holy character of God Himself. Right is right and wrong is wrong, ultimately because God is holy. We have knowledge of what is right and what is wrong because God’s holy character has been revealed by His holy will” (J O Buswell, A Systematic Theology of the Christian Religion [Grand Rapids: Zondervan Publishing House, 1962], 1:67). That is why as Christians, being identified with the holy God, we are called saints.
The word “saint” is the Greek hagios which means “holy one.” The “os” ending of the adjective denotes the idea of possession (Chamberlain, Grammar, 13). In other words, a hagios is one who is characterised by holiness. It must be clarified that when we say a Christian is characterised by holiness, we do not mean he is sinlessly perfect. What we do mean is that as saints, we have been declared righteous, and are positionally sanctified. It does not mean that the sin nature has been totally eradicated. The sinful nature is very much a part of us as long as we are in our mortal bodies.
We constantly experience the struggle between the law of God and the law of sin within us (Rom 7:21-25). But victory is ours when we walk not after the flesh, but after the Spirit (Rom 8:1-4). Therefore, as we progress in our Christian pilgrimage on earth, we should grow more and more Christlike, and be separated from the world and her evil ways.
The Doctrine of Separation and its Application in the Doctrine of the Church.
The Westminster Confession of Faith defines the Church in this way, “The Catholick or universal church, which is invisible, consists of the whole number of elect that have been, are, or shall be gathered into one, under Christ the head thereof; and is the spouse, the body, the fulness of him that filleth all in all. “The visible church, which is also catholick or universal under the gospel, (not confined to one nation, as before under the law), consists of all those throughout the world that profess the true religion, together with their children; and is the Kingdom of the Lord Jesus Christ, the house and family of God, out of which there is no ordinary possibility of salvation” (XXV.1,2).
Our concern in this section is not so much the invisible church, but the visible church—the church here and now seen in the world. The invisible church is perfect. Every true believer, predestined by God, belongs to the invisible church. The church visible, on the other hand, is imperfect. It consists of a “mixed multitude” consisting of both genuine and professing believers. Professing believers are those who claim to be Christians, but actually still unregenerate. The Westminster Confession states, “The purest churches under heaven are subject both to mixture and error; and some have so degenerated as to become no churches of Christ, but synagogues of Satan. Nevertheless, there shall be always a church on earth to worship God, according to his will” (XXV.5).
There is no such thing as a perpetually perfect visible church. It is true that the NT church in the very beginning manifested perfection for “all that believed were together, and had all things common ... continuing daily with one accord.” However, this was but a brief spell for soon there came “a murmuring of the Grecians against the Hebrews, because their widows were neglected.” Later, we read of certain practical problems introduced by false believers which led the Jerusalem Council to decree that the Gentile Christians need not be circumcised (Acts 2:44; 6:1; 15:1-29).
As we read the Epistles, we notice that the Apostles had to address problems within the church. There was not one church that was absolutely free from problems. There was tremendous difficulty in maintaining the unity and purity of the church. False teachers had crept in unawares and brought in damnable heresies (Jude 4, 2 Pet 2:1). This led some churches to move away from the doctrines taught by the Apostles (Gal 1:6, Rev 2-3).
From Jeffrey Khoo was written, he said, although the church is marked by imperfections, it does not mean that we adopt an indifferent attitude and allow such shortcomings to persist. As much as every Christian seeks daily to be more Christlike, so must the church strive to be pure. By virtue of the fact that the church is called ekklesia (lit, “called out”), it is required of her to remain separate. She must be careful to purge herself from all impurities, and keep herself chaste for her Husband—the Lord Jesus Christ. Any wrongful association or unholy yoke is tantamount to adultery.