Romans 1:1 Seperation from non believers

1Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God,

2 Corinthians 614Be ye not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? and what communion hath light with darkness?
15And what concord hath Christ with Belial? or what part hath he that believeth with an infidel?
16And 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.
17Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing; and I will receive you,
18And will be a Father unto you, and ye shall be my sons and daughters, saith the Lord Almighty.