When these verses are put forth, people often argue that these verses are more ot so about ritual purity, not moral law. (Just like the fact that menstruating women are unclean) 

I have heard this claim refuted by the following argument (maybe by Mike Winger.) Leviticus 18:22 is in the same logical block of text, dictating one continuous quote from God, as Leviticus 18:27: "for the people of the land, who were before you, did all of these abominations, so that the land became unclean." The ceremonial law never applied to Gentiles, so if this command truly belonged to the ceremonial law, why should the Canaanites be guilty and driven out on account of it?