There are many many reasons why I don't think God exists.

1: The burden of proof is on the religious, not me. I see no reason to have faith in something that doesn't have any evidence outside of personel experience that cannot be replicated or measured.

2: The God of the gaps. Science is continually shrinking the domain that God exists in. Just because science doesn't understand something today doesn't mean it wont tomorrow and it certainly doesn't mean that God is the explanation anyway. A lot of people tend to jump to the conclusion that since science cannot explain something then "God did it!". Which I think is jumping the gun. I'm not afraid to say I don't know something and I find people that think they have all the asnwers suspect.

3: The inifite regress. Eg. If God made the universe, what made God? Repeat infinity.

4: The plethora of living religions all with adherents that say they all right and the others wrong. They can't all be right.

5: The dead religions that everyone is so dismissive of. I don't find any of the current living religions any more likely to be right.

6: The general move towards monotheism. I go one step further.

7: The idea that some of the current Gods that exist are both omniscient and omnipotent. Which isn;t logically possible since if the future is set in stone and known by the deity they cannot change it (and thus aren't omnipotent) and if they can change it they aren't omniscient.

8: The fact that morality in general is changing, which points towards the fact that morality isn't set in stone in the way some religions think it is.

9: The chauvanism in many of the major religions. The tendency to treat women as a mans possession etc. When I say I think religion is man made, I mean that literally. The chauvanism makes me think that its more likely that men shaped god in their image, not the other way around.

Really I could go on all day. I simply see no reason to be religious. The only reason I had faith in God was because I was born into a faimly that taught me that God exists. If I had been born in India I'd be a Hindu or Iraq I'd have been a Muslim. But being an Atheist was my own conclusion that took years.

You haven't heard of the God gene?    :)

http://www.youtube.com/watch?v=qvijJTjZ8Rg

 The  idea that "spiritual experiences are nothing more than a hallucinations  caused by chemicals in the brain" is also a hallucination caused by chemicals in the brain.

I've studied philosophy, it was obviously a joke.

@smidlee's lastest point

Your arguments are so laughably bad I'm convinced that you have to be joking at this point.

No pic, no proof.

Dude, you don't need anyone's approval if you wish to worship some desert dweller's hallucinations.

Just because drugs can make you see an  pink elephant that not really there does not mean that elephants are not real.  An inbalance in the body (or brain damage) can make someone who is normally happy to have suicide thoughts which it why we say "That person is not themselves."  Scientist themselves speak as if their thought are more than a butch of chemical in their brains.

Well, for starters pink elephants are not real.
Google DMT and search it's effects and also read testimonials from people who have taken it. Also read the sorces that Armad stated in his posts.

When I first met my wife I did nice things for her because I was in love... in another words I have this warm fuzzy feeling as well sexual impulses. These feeling can be easily be explain by some chemicals in the brain. After being married for years this warm fuzzy feeling fades away.  I learned that unlike when we first met , the feelings comes after the action instead of the action after the feeling. It requires hard work to keep a marriage together but afterward the fuzzy feeling does come back from time to time.  I love my wife more now than I did when we first met.  I wonder if the only love some people ever know of is this fuzzy feeling so they will follow one woman( or man)  after another chasing after the feeling like a junkie on drugs.

There is a huge difference in some drug giving someone some kind of "spiritual" feeling and someone being a spiritual person. Drugs can give someone a false peace, joy, love while in reality their life is falling apart , they will steal from even their mother , and are very unhappy. Anyone who had a loved one hooked on drugs will know the difference. Someone who has real peace and love in their heart will have an effect on their bodies (brain) as well.

What's love got to do with it? Seriously, I don't get the point of your first paragraph.

Spirituality doesn't exist. DMT is a substance produced by a gland in the brain. It causes hallucinations. It's normally kept in small quantities, and if the brain accidentally produces too much a person will experience hallucinations which people in the past considered to be spiritual/religions/prophetic visions. Also this substance is released abundantly in the brain when someone dies, hence the visions of people who have near-death experiences.

Spirituality doesn't exist. It's nothin more that hallucinations.

Also you can't get hooked on DMT and it's used in religions practices, even by some christians.