God, Morality, Jesus and the Law

In a comment to my earlier post about the notion that morals can't exist without god, Sis B notes that

Jesus saved us from the "old ways" by dying for us and giving us some sort of direct connection with god, so that we didn't have to make sacrifices or follow all the millions of laws anymore. that was part of how jesus set us free.

I've certainly heard this from Christians, but the relationship between Jesus and Mosaic law is confusing at best. Echoing a passage in the Old Testament where god was very clear about his moral instructions (Deuteronomy 12:32, "See that you do all I command you; do not add to it or take away from it."), Jesus was pretty plainspoken about the matter (Matthew 5:17-20):

Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them. I tell you the truth, 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. Anyone who breaks one of the least of these commandments and teaches others to do the same will be called least in the kingdom of heaven, but whoever practices and teaches these commands will be called great in the kingdom of heaven. For I tell you that unless your righteousness surpasses that of the Pharisees and the teachers of the law, you will certainly not enter the kingdom of heaven.

Of course, starting with Paul, by means of hairsplitting, parsing, and mythmaking, these words were taken to mean something more along the lines of sola fide (that salvation comes from faith alone). These guys, one of a million web sites eager to answer questions about the Bible, cite Paul (Romans 10:4, Galatians 3:23-25, and Ephesians 2:15) more or less plausibly to that effect.

Maybe Jesus invalidated Old Testament laws, and maybe he didn't. In the context of the claim that god is necessary for morality, this creates a pick-your-poison situation for Christians: either he did abolish Old Testament law, in which case sola fide (or something very much like it) is true, and it follows from that doctrine that anything is permissable so long as we hold the right opinions about Jesus; or he didn't abolish Mosaic law, in which case god expects us to stone people to death for mowing the lawn on Sunday. Either way, the god of Christianity makes for a pretty shitty foundation of morals -- or rather an excellent foundation of shitty morals.

Jews and Muslims who still insist that god is the sole and ultimate foundation of morals are, presumably, chomping at the bit to kill their classmates, workmates, friends, and neighbors for all sorts of petty offenses against the almighty. People with genuine morals know better, even if it takes them slightly more effort to explain how they know than gesturing toward a book of fables.