Ezra 9:1-2
After these things had been accomplished, the leaders approached me and said, “The people of Israel, including the priests and Levites, have not kept themselves separate from the surrounding peoples whose abominations are like those of the Canaanites, Hittites, Perizzites, Jebusites, Ammonites, Moabites, Egyptians, and Amorites. / Indeed, the Israelites have taken some of their daughters as wives for themselves and their sons, so that the holy seed has been mixed with the people of the land. And the leaders and officials have taken the lead in this unfaithfulness!”

Deuteronomy 7:3-4
Do not intermarry with them. Do not give your daughters to their sons or take their daughters for your sons, / because they will turn your sons away from following Me to serve other gods. Then the anger of the LORD will burn against you, and He will swiftly destroy you.

1 Kings 11:1-4
King Solomon, however, loved many foreign women along with the daughter of Pharaoh—women of Moab, Ammon, Edom, and Sidon, as well as Hittite women. / These women were from the nations about which the LORD had told the Israelites, “You must not intermarry with them, for surely they will turn your hearts after their gods.” Yet Solomon clung to these women in love. / He had seven hundred wives of royal birth and three hundred concubines—and his wives turned his heart away. ...

Exodus 34:15-16
Do not make a covenant with the inhabitants of the land, for when they prostitute themselves to their gods and sacrifice to them, they will invite you, and you will eat their sacrifices. / And when you take some of their daughters as brides for your sons, their daughters will prostitute themselves to their gods and cause your sons to do the same.

Malachi 2:11
Judah has broken faith; an abomination has been committed in Israel and in Jerusalem. For Judah has profaned the LORD’s beloved sanctuary by marrying the daughter of a foreign god.

Judges 3:5-6
Thus the Israelites continued to live among the Canaanites, Hittites, Amorites, Perizzites, Hivites, and Jebusites. / And they took the daughters of these people in marriage, gave their own daughters to their sons, and served their gods.

2 Corinthians 6:14-17
Do not be unequally yoked with unbelievers. For what partnership can righteousness have with wickedness? Or what fellowship does light have with darkness? / What harmony is there between Christ and Belial? Or what does a believer have in common with an unbeliever? / What agreement can exist between the temple of God and idols? For we are the temple of the living God. As God has said: “I will dwell with them and walk among them, and I will be their God, and they will be My people.” ...

1 Corinthians 7:39
A wife is bound to her husband as long as he lives. But if her husband dies, she is free to marry anyone she wishes, as long as he belongs to the Lord.

Joshua 23:12-13
For if you turn away and cling to the rest of these nations that remain among you, and if you intermarry and associate with them, / know for sure that the LORD your God will no longer drive out these nations before you. Instead, they will become for you a snare and a trap, a scourge in your sides and thorns in your eyes, until you perish from this good land that the LORD your God has given you.

1 Kings 16:31-33
And as if it were not enough for him to walk in the sins of Jeroboam son of Nebat, he even married Jezebel the daughter of Ethbaal king of the Sidonians, and he then proceeded to serve and worship Baal. / First, Ahab set up an altar for Baal in the temple of Baal that he had built in Samaria. / Then he set up an Asherah pole. Thus Ahab did more to provoke the LORD, the God of Israel, to anger than all the kings of Israel before him.

2 Kings 17:7-8
All this happened because the people of Israel had sinned against the LORD their God, who had brought them out of the land of Egypt from under the hand of Pharaoh king of Egypt. They had worshiped other gods / and walked in the customs of the nations that the LORD had driven out before the Israelites, as well as in the practices introduced by the kings of Israel.

1 Corinthians 5:9-11
I wrote you in my letter not to associate with sexually immoral people. / I was not including the sexually immoral of this world, or the greedy and swindlers, or idolaters. In that case you would have to leave this world. / But now I am writing you not to associate with anyone who claims to be a brother but is sexually immoral or greedy, an idolater or a verbal abuser, a drunkard or a swindler. With such a man do not even eat.

2 Corinthians 11:2-3
I am jealous for you with a godly jealousy. For I promised you to one husband, to present you as a pure virgin to Christ. / I am afraid, however, that just as Eve was deceived by the serpent’s cunning, your minds may be led astray from your simple and pure devotion to Christ.

1 Peter 2:9-12
But you are a chosen people, a royal priesthood, a holy nation, a people for God’s own possession, to proclaim the virtues of Him who called you out of darkness into His marvelous light. / Once you were not a people, but now you are the people of God; once you had not received mercy, but now you have received mercy. / Beloved, I urge you, as foreigners and exiles, to abstain from the desires of the flesh, which war against your soul. ...

Romans 12:2
Do not be conformed to this world, but be transformed by the renewing of your mind. Then you will be able to test and approve what is the good, pleasing, and perfect will of God.