Leviticus 20:5

then I will set My face against that man and against his family, and will cut him off and all that go a-whoring after him, in the double sense of committing an immoral act and of becoming guilty of idolatry, to commit whoredom with Molech, from among their people. As no sacrifice to false gods was permitted in the land, so this special worship of Molech was an abomination which could under no circumstances be tolerated.