So be very careful to follow everything Moses wrote in the Book of Instruction. Do not deviate from it, turning either to the right or to the left. Make sure you do not associate with the other people still remaining in the land. Do not even mention the names of their gods, much less swear by them or serve them or worship them. Rather, cling tightly to the LORD your God as you have done until now. “For the LORD has driven out great and powerful nations for you, and no one has yet been able to defeat you. Each one of you will put to flight a thousand of the enemy, for the LORD your God fights for you, just as he has promised. So be very careful to love the LORD your God. “But if you turn away from him and cling to the customs of the survivors of these nations remaining among you, and if you intermarry with them, then know for certain that the LORD your God will no longer drive them out of your land. Instead, they will be a snare and a trap to you, a whip for your backs and thorny brambles in your eyes, and you will vanish from this good land the LORD your God has given you.
Joshua 23:6-13 NLT