Why do people think that Xtians have to follow the Law of Moses? The letters of the NT and Acts (Council of Jerusalem around chapter 15, I think) have a lot to say on Jesus fulfilling the law so that non-Jews don't have to follow it. Xtians do not follow the 613 laws of the Hebrew Scriptures.
Or, do you all know this and are successfully enjoying tying DOC in knots, in which case, carry on.
But then people, especially in the US, insist on putting the 10 commandments in public places or quote Leviticus by calling gays 'abomination'...
As you mention, Jesus did talk about fulfil the laws -fulfill, rather than "detroy". In the next sentence, however, he also mentions that "until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished".
So; the idea that Jesus did render the ancient Israelite practices obsolete was clearly not in the texts. This interpretation, in my opinion, is really stretching the meaning of the term 'fulfil'.
But then, he kinda contradicts this statement by discarding the idea of diet purity...
For an atheist, that is not really a problem.
Jesus might have interpreted the Old testament's commandments in the light of the Greco-Roman influenced first century Palestine. A mistake in regard to the position of the original writers, a there is no evidence to indicate that the Laws were ever seen as anything but literal.
Or his position might have been modified or exaggerated by later writers to lend support to Paul's position in face of Jame's. The gospels were, after all, probably written in churches founded by Paul himself and doing away with the old Jewish practices was probably necessary to attract gentiles to the budding Religion. Without them, Christianity would have either withered or just become one of the component of proto-rabbinic Judaism.