Then the Lord spoke to Moses, saying, “Again, you shall say to the children of Israel: ‘Whoever of the children of Israel, or of the ger who dwell in Israel, who gives any of his descendants to Molech, he shall surely be put to death. The people of the land shall stone him with stones. I will set My face against that man, and will cut him off from his people, because he has given some of his descendants to Molech, to defile My sanctuary and profane My holy name. And if the people of the land should in any way hide their eyes from the man, when he gives some of his descendants to Molech, and they do not kill him, then I will set My face against that man and against his family; and I will cut him off from his people, and all who prostitute themselves with him to commit harlotry with Molech.What Does It Say?
Leviticus 20 is also mostly a list of prohibitions, with one distinct difference from Leviticus 19. Whereas Leviticus 19 has a mixture of both positive and negative commandments (a mix of "do this" and "don't do that"), Leviticus 20 is a list of offensive that warrant the death penalty. In addition to the section quoted above, the chapter lists other capital offenses, such as:
-Consulting familiar spirits (spiritism)
-Cursing your parents
Now, a few of these commandments specify that a person who does these things shall be 'cut off' and some of them specify stoning as a method of execution. I suppose you could argue that 'cutting off' is a form of exile, but it's also used to describe the people who perished in Noah's Flood (Gen. 9:11). Most likely, it just means that the method of death does not need to be stoning. In fact, the penalty for consulting a spirit medium is that God Himself will cut off the offender (v. 6).
Molech, of course, is a Canaanite diety who was worshiped by human sacrifice. So 'giving your descendants to Molech' does not mean consecrating them to the worship of the false god, but rather burning them in an unholy sacrifice. This shows why the offense of Molech worship was so evil that it required the death penalty, whether the offender was a native Israeli or a ger.
Once again, we see that ger are particularly required to observe the same religious laws as the Israelis in order to dwell in the land.
Next: Leviticus 22