Be you not unequally yoked together with unbelievers: for what fellowship has righteousness with unrighteousness? and what partnership has light with darkness?
All Commentaries on 2 Corinthians 6:14 Go To 2 Corinthians 6
The Apostolic Constitutions
AD 375
Let not one of the godly pray with an heretic, no, not in the house. For "what fellowship hath light with darkness? "