Yes you make a good point. And those are written very recently, in the same language and notably are constantly being revised (which isn't happening with any religious books).
Instead people pick and choose the bits in the bible that fit with their real beliefs. Either writing off things as "not meant to be taken literally" or just simply glossed over. And many of our social standards and moral have come a long way since the old testament.
Imagine if there really is a god, how much you could piss him off just by meaning well but accidentally getting his instructions wrong!
How secure can you really be in your knowledge of any god's supposed will?
Food for thought I hope.