Deuteronomy 7:1-4
When the LORD your God brings you into the land that you are entering to possess, and He drives out before you many nations—the Hittites, Girgashites, Amorites, Canaanites, Perizzites, Hivites, and Jebusites, seven nations larger and stronger than you— / and when the LORD your God has delivered them over to you to defeat them, then you must devote them to complete destruction. Make no treaty with them and show them no mercy. / Do not intermarry with them. Do not give your daughters to their sons or take their daughters for your sons, ...

Exodus 34:11-16
Observe what I command you this day. I will drive out before you the Amorites, Canaanites, Hittites, Perizzites, Hivites, and Jebusites. / Be careful not to make a treaty with the inhabitants of the land you are entering, lest they become a snare in your midst. / Rather, you must tear down their altars, smash their sacred stones, and chop down their Asherah poles. ...

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.

Psalm 106:34-36
They did not destroy the peoples as the LORD had commanded them, / but they mingled with the nations and adopted their customs. / They worshiped their idols, which became a snare to them.

Nehemiah 13:23-27
In those days I also saw Jews who had married women from Ashdod, Ammon, and Moab. / Half of their children spoke the language of Ashdod or of the other peoples, but could not speak the language of Judah. / I rebuked them and called down curses on them. I beat some of these men and pulled out their hair. Then I made them take an oath before God and said, “You must not give your daughters in marriage to their sons or take their daughters as wives for your sons or for yourselves! ...

1 Kings 11:1-2
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.

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!”

Numbers 33:55-56
But if you do not drive out the inhabitants of the land before you, those you allow to remain will become barbs in your eyes and thorns in your sides; they will harass you in the land where you settle. / And then I will do to you what I had planned to do to them.”

Deuteronomy 20:16-18
However, in the cities of the nations that the LORD your God is giving you as an inheritance, you must not leave alive anything that breathes. / For you must devote them to complete destruction—the Hittites, Amorites, Canaanites, Perizzites, Hivites, and Jebusites—as the LORD your God has commanded you, / so that they cannot teach you to do all the detestable things they do for their gods, and so cause you to sin against the LORD your God.

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 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.

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.

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.

Hosea 7:8-9
Ephraim mixes with the nations; Ephraim is an unturned cake. / Foreigners consume his strength, but he does not notice. Even his hair is streaked with gray, but he does not know.

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.