If I came across this sort of phrasing in some other context and were forced to interpret it, I'd think that "so what" would mean "the point" or "the reason why something is important." In other words, if somebody asks "so what," you provide, hopefully, a reason why what you're talking about is significant.
I agree with bibliolept that the sentence is odd and difficult to understand. Is it from a book? Was it written by a native speaker?
It is likely that the writer intended the meaning that biblio suggests but the sentence as written is far from clear.
EDIT: It appears that there is a catch phrase currently in academic use, "the so what question". From what I gather, this means "the implications". If that is your author's usage, the sentence makes perfect sense: he is saying that all the rules of Israel's Law implied the law of love.