Charles Spurgeon Commentary 2 Corinthians 6:14

"Be not unequally yoked with unbelievers: for what fellowship have righteousness and iniquity? or what communion hath light with darkness?" — 2 Corinthians 6:14 (ASV)

For what fellowship hath righteousness with unrighteousness?

and what communion hath light with darkness?

You must be in the same world with them, but keep yourself distinct from them. Do not go into their society by your own choice, nor seek your pleasure with them.

Be ye not unequally yoked together with unbelievers:

Not in any way – neither in marriage, which is the chief of all forms for yoking, nor in business or other partnerships.