It is quite clearly originally meant to apply to Israelites – “the children of thy people”. As the Bible was later consecrated into Scripture, it now applies to all Christians.
Leviticus has lots of interesting goodies, one of my favourites it the fact that it makes it quite clear that there are other Gods and that the Christian God will get pissed off if you worship them. See Leviticus 18:21 / 20:2–5 Christians keep using the Bible to claim that there is no other God, not that you should only worship this one particular God.
And thou shalt not let any of thy seed pass through the fire to Molech, neither shalt thou profane the name of thy God: I am the LORD.
(Leviticus 18:21)
Again, thou shalt say to the children of Israel, Whosoever he be of the children of Israel, or of the strangers that sojourn in Israel, that giveth any of his seed unto Molech; he shall surely be put to death: the people of the land shall stone him
(Leviticus 20:2)
And I will set my face against that man, and will cut him off from among his people; because he hath given of his seed unto Molech, to defile my sanctuary, and to profane my holy name.
(Leviticus 20:3)
And if the people of the land do any ways hide their eyes from the man, when he giveth of his seed unto Molech, and kill him not:
(Leviticus 20:4)
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, to commit whoredom with Molech, from among their people.
(Leviticus 20:5)
God seems to get a bit twisted when anyone sides with the opposition. Not very Christian is it?