"Do not be unequally yoked together with unbelievers."

We then, as  workers together with Him also plead with you not to receive the grace of God in vain. For He says: “”Behold, now is the accepted time; behold, now is the day of salvation. We give no offense in anything, that our ministry may not be blamed. But in all things we commend ourselves as ministers of God: in much patience, in tribulations, in needs, in distresses, in stripes, in imprisonments, in tumults, in labors, in sleeplessness, in fastings; by purity, by knowledge, by longsuffering, by kindness, by the Holy Spirit, by sincere love, by the word of truth, by the power of God, by the armor of righteousness on the right hand and on the left, by honor and dishonor, by evil report and good report; as deceivers, and yet true; as unknown, and yet well known; as dying, and behold we live; as chastened, and yet not killed; as sorrowful, yet always rejoicing; as poor, yet making many rich; as having nothing, and yet possessing all things. O Corinthians! We have spoken openly to you, our heart is wide open. You are not restricted by us, but you are restricted by your own affections. Now in return for the same (I speak as to children), you also be open. Do not be unequally yoked together with unbelievers. For what fellowship has righteousness with lawlessness? And what communion has light with darkness? And what accord has Christ with Belial? Or what part has a believer with an unbeliever? And what agreement has the temple of God with idols? For you are the temple of the living God. As God has said: “I will dwell in them And walk among  them. I will be their God, And they shall be My people.” Therefore “Come out from among them And be separate, says the Lord. Do not touch what is unclean, And I will receive you.” “I  will be a Father to you, And you shall be My  sons and daughters, Says the  Lord  Almighty.” 2 Corinthians 6:1-18 - NKJV