Lol, getting into Old vs. New Covenant could really open up a can of worms. From what I've seen, the OT has two sets of laws: the Ten Commandments (which are still binding, as Jesus kept them and never mentioned them disappearing), and the rest (which, although the principles behind them are still sound, the actual laws were designed for the culture and place that the Israelites were, and no longer apply to us today). I believe there's a couple differing views of that out there, though. Some believe all the ritual laws still apply today (and I wonder what they do because they don't have a temple to go sacrifice at), and others believe the Ten Commandments are somehow done away with now . . .
The Old Testament religion wasn't really based on works either--it's not like the sacrifice of the animal actually did take away the sins--but it was based on the hope of the future Sacrifice yet to come, and all the ritual was designed in a way to point minds and hearts towards the future Messiah, to help people see the gravity of their sins and repent. But God has never operated on works--the Israelites could no more earn their way to heaven than we can today. Salvation was a promised gift then, and it's a waiting gift now.
