Be Not Joined To Unbelievers
“Be not unequally yoked together with unbelievers: for what fellowship hath righteousness with unrighteousness? And what communion hath light with darkness? And what concord hath Christ with Belial? Or what part hath he that believeth with an infidel? . . .”
(2nd Corinthians 6:14-16)
This command is so plain, that it requires no interpreter. Righteousness and wickedness; light and darkness; Christ and the Devil; God’s temple and idols . . . What do they have in common? This is a call to godly separation. This passage gives utterance to a Divine exhortation for those belonging to Christ . . . to hold aloof from all intimate associations with the ungodly. It expressly forbids them entering into alliances with the unconverted. It definitely prohibits the children of God walking arm-in-arm with worldlings. It is an admonition applying to every phase and department of our lives . . religious, domestic, social, commercial. And never, perhaps, was there a time when it is more needed, more pressing on Christians, than now. The days in which we are living are marked by the spirit of compromise. On every side we behold unholy mixtures, ungodly alliances, and unequal yokes. Many professing Christians appear to be trying how near to the world they may walk–and yet go to Heaven!
To Israel, God said, “After the doings of the land of Egypt, wherein ye dwelt, shall ye not do: and after the doings of the land of Canaan, whither I bring you, shall ye not do: neither shall ye walk in their ordinances. Ye shall do my judgments, and keep mine ordinances, to walk therein: I am the LORD your God.” (Leviticus 18:3-4) And again, “And ye shall not walk in the manners of the nations, which I cast out before you: for they committed all these things, and therefore I abhorred them.” (Leviticus 20:23) It was for their disregard of these very prohibitions, that Israel brought down upon themselves such severe chastisements.
God’s call to His people in Babylon is, “Come out of her, my people, that ye be not partakers of her sins, and that ye receive not of her plagues.” (Revelation 18:4) No one can be a whole-hearted follower of the Lord Jesus who is, in any way, “yoked” to His enemies!
Arthur Pink
Test All Things 
Numbers 33:55
But if ye will not drive out the inhabitants of the land from before you; then it shall come to pass, that those which ye let remain of them shall be pricks in your eyes, and thorns in your sides, and shall vex you in the land wherein ye dwell.
Numbers 33:56
Moreover it shall come to pass, that I shall do unto you, as I thought to do unto them.
What are the lessons learned from the above status of the LORD God’s stern commandments of the ancient Israelites and their utter failures over and over and over again to come out from the wicked world?
2nd Corinthians 6:14
Be YE NOT UNEQUALLY YOKED TOGETHER WITH UNBELIEVERS: for what fellowship hath righteousness with unrighteousness? and WHAT COMMUNION HATH LIGHT WITH DARKNESS?
2nd Corinthians 6:15
And WHAT CONCORD [AGREEMENT, PART] hath Christ with Belial? or WHAT PART hath HE THAT BELIEVETH with AN INFIDEL?
2nd Corinthians 6:16
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.
2nd Corinthians 6:17
Wherefore COME OUT FROM AMONG THEM, and BE YE SEPARATE, saith the Lord, and TOUCH NOT THE UNCLEAN THING; and I will RECEIVE YOU.
2nd Corinthians 6:18
And WILL be a FATHER UNTO YOU, and YE SHALL be MY SONS and DAUGHTERS, saith the Lord Almighty.