Ok... let's clarify a few matters of the laws first. The Mosaic laws were a judicial system set up by God for rulership of a theocracy. We do not currently live in an Abrahamic theocracy, so those laws no longer apply. Secondly, the Sabbath rest was instituted at creation to be kept in rememberance by all of mankind, not simply Jews of the OT. God made this clear by holding it up in the Decalogue, His moral 10 commandments (which incidentally have never been done away with as many suppose). Therefor, all mankind are to honor God by keeping the ten commandment Sabbath (Saturday) but aren't to be punished by death here and now. Actually, those who do not love Christ by keeping the commandments of God will pay via eternal death in the lake of fire later.
http://sabbathtruth.org/
http://www.the-ten-commandments.org/
http://helltruth.com/