As pointed out before, the Christian church obsoleted the Jewish covenent. Presumably, the theologically correct justication is that Jesus Christ, being an officially appointed prophet, taught a shiny, new philosophy and replaced the package deal with god. This includes transferring faith from the Old Testament to the New. This would explain the radical differences between the two and why Christians can ignore the contradictions. The Old Testament has been divinely demoted to an historical archive, its wisdom is no longer the best and any laughable stories were merely a useful fiction to sustain ancient Israelites.
That certain churches quote from the Old Testament as if it trumps man-made philosophies merely indicates they don't understand their own religion. As the New Testament does not mention sodomy, god hated 'fags' in the past but is now indifferent.
So, when a 'Christian' quotes from the old book, how can he be correctly informed that it's obsolete, preferably by quotes from the new book?