"And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ:" - Ephesians 4:11-13
"And that ye put on the new man, which after God is created in righteousness and true holiness." - Ephesians 4:24
The example that believers have to follow is, of course, that of the Son of God who shows to all the characteristics of his Father. One of the requirements for the perfecting of the saints is the "unity of the faith, and of the knowledge of the Son of God". Unity of the faith requires the refusal to accept doctrinal error and the removal from fellowship of those who continue to hold to such errors (2 Corinthians 6:14-182 Corinthians 6:14-18 14 Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness? 15 And what concord hath Christ with Belial? or what part hath he that believeth with an infidel? 16 And what agreement hath the temple of God with idols? for ye are the temple of the living God; as God hath said, I will dwell in them, and walk in them; and I will be their God, and they shall be my people. 17 Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you, 18 And will be a Father unto you, and ye shall be my sons and daughters, saith the Lord Almighty.).
Holiness is not simply separation but the separation that knowing and understanding the Truth brings. The converse being that holiness cannot be achieved without knowing the Truth since holiness requires a two-stage process, knowledge and acceptance, which together bring obedience to the Word of God, and in turn bringing about the rejection of false doctrine. Some Bible versions more accurately translate the end of verse 24 as "holiness of truth", which gives a different meaning to the phrase by removing the inference of holiness without truth and stating that holiness is only possible in conjunction with truth. Therefore, as truth is absolute any false doctrine results in the absence of holiness; something that we all should be cognizant of and ensure that we are not defiled thereby.