First, Trevrawr, welcome to TFP
No question about it, the universe is filled with many incredible things. I don't think that, in itself, makes it any more likely that there is an intelligent designer though. As humans, we're genetically predisposed to see patterns and attribute meaning to things. What we fail to notice, or give appropriate attention to, is that for all its wondrous complexity, life and Earth are terribly inefficient. If you learn enough about the science behind creation, it becomes clear that if there is a "creator," it's questionable whether or not that creator is actually intelligent.
But why not believe in one anyway? There are two main reasons. First, belief often comes with other requirements, so it is not true to say there's no harm in believing even if it's not true. Just going to church for an hour a week would waste about 4 months over the course of your life, not to mention potentially unnecessary moral hangups that are often associated with belief. Second, we have a fairly robust history as humans of seeking truth for its own sake. I see no reason to stop when it comes to matters of spirituality.
There are valid arguments on both sides when it comes to disproving another person's faith. In a discussion like this one, I see no reason why anyone should hold back. It's on-topic, and it makes no sense to say the believer can make arguments for belief but the atheist cannot make arguments for skepticism. I don't think you mean conversations like this one though, I think you're talking about the world at large. In that case, I cautiously agree. Atheist evangelism is just as annoying and inappropriate as any other sort of evangelism. That doesn't mean atheists should pretend they don't exist though. Demands for equal respect are often framed by believers as an attack on faith, but it really comes down to religious freedom. To an atheist, having "god" in the pledge, for example, is just as appalling as it would be for a Christian if the pledge said "under Krishna." A Christian would not be persecuting Hindu's by demanding Krishna be removed from the pledge, that Christian would simply be demanding that the country live up to the secular ideals it was founded under. (Indeed, "under God" was not added to the pledge until the 1950's).
This brings us back to intelligent design. One could read what I wrote above and think that is an argument for teaching intelligent design in schools. It is not. There is a significant difference between recognizing the rights of people to believe what they wish, and promoting particular beliefs. Where science differs from intelligent design and other theories on creation is that science is verifiable. We have a responsibility in our schools to only teach things that are generally known to be factual. There is ample evidence for evolution and an Earth that is about 4.5 billion years old. There is, literally, no evidence at all that there is an intelligent designer. People have a right to believe in one, but we should not specifically teach things that have no basis in verifiable fact.
Finally, I feel I should address the idea that whoever is right we should hope the theoretical intelligent designer is forgiving. This is, of course, another problem with intelligent design: it's just a veiled term for creationism and conservative Christian values. Plenty of other religions have no concept of a creator that judges, and apparently these religions do not fit into the intelligent design paradigm. Even if there is an intelligent designer, why would this being be particularly concerned with what we think of him? There are an estimated 6.25 billion life-supporting solar systems in the universe, and absent evidence that we are alone in the universe it is safe to assume that there is plenty of intelligent life out there beyond our communication capabilities. I see no reason to believe that if there were an intelligent designer, it would be so narcissistic as to demand all these species believe despite no evidence or face punishment. In fact, the whole concept of a deity that punishes people for lack of belief is appalling, particularly when you consider that lack of belief often comes from people using the very cognitive abilities the supposed creator gave us. Kind of sadistic, don't you think?
Anyway, despite the rant I do mean it: welcome to TFP
If you have any questions or concerns, please feel free to PM me or any of the other moderators!