That doesn, really, excuse the contradicitions though.
The Bible is, supposedly, Gods Word. And his word is, supposedly, Absolute. If his word is Absolute, then why does it change? And if his word can change, then how are we to know if what we are following matches Gods current word?
Frankly, justifying the change in views doesn't strengthen Christianity. It weakens it, and gives truth to Islam. (His word, has, apparently changed once. For what we know, Islam is true to his current word.) Or whatever the most recent, God inspired, Religion is.