Charles Ellicott Commentary Leviticus 20:5

"then I will set my face against that man, and against his family, and will cut him off, and all that play the harlot after him, to play the harlot with Molech, from among their people." — Leviticus 20:5 (ASV)

Then I will set my face. — In that case God himself will show His anger. (See Leviticus 20:3 and Leviticus 17:10.) He will interpose to execute just judgment.

And against his family. — Because they would naturally be privy to it, and aid and abet the father in this crime, they, as well as all those who joined in this idolatrous worship, will be cut off by God himself.