So then, the question becomes "When was the Bible corrupted?"  One possibility is before the Koran was written in the seventh century.  The problem with this possibility is that the Koran itself refers to the Bible as a reliable document at the time in which the Koran was written.

For example, Koran 5:47 says "Let the People of the Gospel [i.e., Christians] judge by what God hath revealed therein.  If any do fail to judge by the light of what God hath revealed, they are no better than those who rebel."  This is a call issued by the Koran in the seventh century for Christians to listen to what God had revealed in the New Testament.  This call only makes sense if the New Testament had been faithfully preserved through the seventh century, because only then could they "judge by the light of what God hath revealed."

Likewise, Koran 5:68 says "Say: ‘O People of the Book [i.e., Jews and Christians]!  Ye have no ground to stand upon unless ye stand fast by the Law [i.e., the Old Testament], the Gospel [i.e., the New Testament], and all the revelation that has come to you from your Lord.'"  Again, this assumes that the Bible is reliable at the time of the writing of the Koran because you can't "stand fast" by what has essentially been lost through corruption.

So, the Koran itself assumes that the Bible had been faithfully preserved, at least through the seventh century when the Koran was written.  Of course, for Islam to suggest that the Bible had become fundamentally corrupted before the seventh century would lead to a contradiction, causing Islam to fail the Test of Logical Consistency.

Of course, the other possibility is that the Bible came to be corrupted at some point after the seventh century.  The problem with this is that we have a massive amount of New Testament manuscripts dating as far back as the second century and Old Testament manuscripts dating back even earlier that are virtually identical with our Bibles today.  This rules out the possibility of the kind of Biblical corruption that Islam requires after the second century.  And of course, for Islam to suggest that the Bible had become fundamentally corrupted after the second century would simply clash with history, causing Islam to fail the Test of Historical Consistency.

So where does that leave us?  The Koran does not allow for a corrupted Bible before the seventh century.  History itself shows that the Bible could not have been corrupted after the second century.  So there is no time left in which the Bible could have been corrupted.  And since Islam depends on the notion that the Bible has been fundamentally corrupted, we see that Islam as a worldview cannot fit reality.

What About Tolerance?  

With all this talk about different worldviews failing to fit reality, you might wonder what happened to tolerance.  It sure doesn't sound tolerant, does it?  But what is tolerance?

Our modern notion of tolerance is that you can't say that someone else's beliefs are wrong.  If you do, you are being intolerant.  But that is not what tolerance has always meant.  The historic meaning of tolerance is that you should be willing to live peacefully and respectfully with those you believe, and even say, are wrong.

If you think about it, our modern "redefined" understanding of tolerance doesn't even make sense.  If you can't say something is wrong or false, there is nothing left to tolerate.

But even more than this, our modern understanding of tolerance undercuts itself.  It does the very thing that it claims ought not to be done.  It says, essentially, that it is wrong for you to say that someone else is wrong.  This, of course, fails the Test of Logical Consistency, and thus cannot be an approach that fits reality.