I have a question for fundamentalist Christians and true believers of all stripes: How is that you happen to know the truth and no one else does? I can think of several possible answers:
(1) You are more sincere. This answer is appealing. Even so, I think if any of us are honest and actually get out and meet people who see the world differently than we do, we'll come across many people who are completely sincere. There are, after all, people who have devoted their lives to their particular path at tremendous sacrifice. Yet all of these sincere people do not happen to share the same set of beliefs.
(2) You are more intelligent. This answer doesn't get very far. Since there exist people on the far right tip of the intelligence bell curve in most religious traditions and among athiests, this response only works for those who are beyond Einstein or Hawkins' level of intelligence.
(3) Truth is given to people as a form of grace from some higher power. This answer makes sense. I'm reminded of Koranic passages describing how Allah clouded people's eyes so that they wouldn't see the truth. It is, of course, extremely unappealing. If truth is bestowed on us from above, there's no reason to discuss it in a public forum. Truth, in this bizarre scenario, isn't something public. You either have the high-speed fiber optic connection to the holiest of holies or you don't, and there's absolutely nothing you can do to get your own house wired. In such a bizarro world, there's also no need to go out and try to convince others. Since God (or Satan, or Descarte's demon) has clouded the eyes of other people, they'll never know the truth. Of course, there's also no way to know exactly who's eyes have been clouded, but we shouldn't dwell on this fact for too long lest we end up jumping from dogmatism into full-blown skepticism.
(4) Of course, we could adopt the view of science and conclude that truth is knowable and public, that is does make sense to discuss matters, and that a meaningful consensus is possible. The ability to reach truth would then have something to do with intelligence and sincerity. The fact that scientists from around the globe are perfectly able to come to complete agreement about pretty much all of the facts that aren't on the current horizon of human knowledge is certainly remarkable compared to the so-called facts of religion. To give religion its due, I don't think that most fields of science address some key issues that must be addressed, such as what it means to live a beautiful and fullfilled life, but these issues, much like scientific issues, can still be addressed through discussion and agreement of sorts can be reached. I think Snoopy has it right in the following comic: