Please do read these articles in order. There is a certain logic behind it which will otherwise get lost. Especially do not skip over the preface and the introduction.
The Claim of Universality:
Simplicity and Truth
Morality and Character issues:
... more to come ...
Copyright © 1997 Jochen Katz. All rights reserved.
Further collections of questions and reasons why Christians are sceptical about Islam:
Answering Islam Home Page