Slightly different than my other active topic "Why atheism", this topic seeks to focus more on that idea concerning whether God exists or does not exist. It will focus more on the concept of God, so what religion one may be shouldn't have much of an affect the discussion as much as it normally would (but nonetheless still there).
If you believe in God, explain your understanding of God (for example, if you are a deist, you might believe that there is definitely a God, but he doesn't care for his creations, or that God is a man, etc.)
If you do NOT believe in God (which would be the majority of the people who are going to contribute to this thread), explain why you don't believe that God exists and maybe even what led you to believe that way.
Remember to keep the discussion calm and clean so as to make the experience as enjoyable and informative as possible.
To start off, personally, I will be posting several articles that give the Islamic perspective as to why without a doubt a single Creator with infinite power exists, and the absolute proofs that there actually IS a God, and attempt to show that those who do not recognize His blatant existence are truly blind (that is simply my message and isn't meant to offend anyone).
EDIT: January 25th, 2010: Here's a video of the answer in the Islamic perspective, very easy to follow and is worth watching and is enjoyable. Don't let the video length scare you, or don't skip around should you decide to watch the video in its entirety. Answers a lot of questions and touches on many subjects concerning if God exists. There is some terminology that will definitely be foreign to you (he uses a few Arabic words, but don't worry the video is in English), and I will try my best to aid you in what he meant when explaining something or responding to someone. The actual lecture starts at about a minute and twenty seconds in.