"Each requires faith, not reason, to be accepted by the respective believers. Arguing over which one is 'right' seems difficult."
Faith and reason go hand in hand when it comes to the Bible. This is not so with the koran. Again contrary to your who is "right" ... it is the Bible that is right. If you'd read it, you'd know that to be true. Those who know the Bible as being "right" don't have the difficulty of seeing where the koran is wrong, contradictory and illogical. It's just another blessing from being familiar with the Word of God. BTW, God isn't relative either. Right and wrong are clearly written about.
I like this verse on reasoning:
Isa.1:18
[18] Come now, and let us reason together, saith the LORD: though your sins be as scarlet, they shall be as white as snow; though they be red like crimson, they shall be as wool.
What the Lord is saying is that believing in Him and His teachings is not unreasonable and neither is faith in Him.