This was posted up here by Mr Friday a former member in 2008. I hope it helps.
" Reasons for not believing
* There is not one iota of unequivocal evidence that any God exists.
* God cannot explain all that exists because God itself cannot be explained. This claim just gratuitously swaps one mystery for another.
* Religions do not explain any mechanism or process whereby God created everything. It is effectively an appeal to magic.
* Religious faith is generally indistinguishable from gullibility. Trust and faith, as human concepts, are normally based on experience and reason. Religious faith is necessarily based on belief in unproved and unknowable things.
* A god or anything that exists outside the realm of natural reality is necessarily unknowable, unintelligible and incoherent. It is therefore irrational to believe in something that is supernatural.
* Religious scripture:
o is man-made
o contains many translation and interpretation errors
o is often self-contradictory
o often contradicts known facts
o promotes conversion by violence
o calls for punishment and death to unbelievers
o contains virtually no specific and unequivocal predictions
o contains only vague predictions beyond its own time
o contains many failed prophecies, predictions and unfulfilled promises of God
* Scripture contains too much that is vague, metaphorical and symbolic to be instructions from a divine being to humans. A perfect being would be expected to be able to communicate much better than that.
* In order to render most of scripture useful, it must necessarily be interpreted. This makes it easily twisted to support nefarious purposes.
* The problems with scriptures outweigh any good messages they may contain. If read at all, they should be considered opinion and philosophy and taken with a grain of salt.
* Morals are based on human sympathy and empathy, not on divine guidance. Establishing moral codes based on theism is unnecessary, riddled with contradictions, and fraught with danger.
* Religion is divisive in that it pits groups of otherwise indistinguishable people against one another. There are already more than enough differences for humans to fight over. And religion is the most intransigent of such divisions because many people feel it is a divine duty to revile those who believe differently than they do even if they don't see the reason in it.
* Religions are generally intractable when it comes to substantive compromise with other religions or belief systems.
* All suggested ways to perceive God rely on internal mechanisms that are subject to personal desires, suggestion, and mistakes. On the question of communicating with God, religion insidiously asks us all to deceive ourselves.
* People are animals. We are only special due to our more developed brain. (We share 98% of our DNA with chimpanzees)
* Abrahamic religions teach that the earth is only about 6000 to 10000 years old. All claims of a young earth are refuted by volumes of clear and mutually corroborating evidence in multiple scientific disciplines as well as a host of mutually confirming dating techniques that are not subjective or rationalized.
* Every culture that has existed has had God myths and other superstitions. This is often used as an argument for the existence of God. Rather than indicating that there is a true God, this indicates that people are simply attracted to the idea.
* Goodness, truth, wisdom and all other purported attributes of God are human concepts. When applied to a presumed entity so completely different in kind as to be supernatural, they are meaningless. The idea of God is thus incoherent.
* Infinity is a concept humans cannot comprehend except in a limited mathematical sense. If God is infinite, this also renders him unintelligible.
* Belief in an afterlife is insidious and detrimental to social responsibility and mental health. It demeans actual life and frequently leads to the notion that killing someone is, at least conceivably, doing them a favor.
* Organized religion wastes untold amounts of money and resources that could be used to care for people, promote real knowledge, and advance the human race.
* Theism puts God above people thereby making people subservient, unimportant and expendable.
* Religion relies on guilt, fear and outlandish promises to gain obedience.
* Theism generally precludes any possibility of testing God or questioning his existence substantively. It is something like the wizard of Oz saying, "Pay no attention to the man behind the curtain."
* The methods used in proselytizing for religion bear an unmistakable resemblance to the methods of confidence men. But the scriptures consider this the great commission of mankind.
* There are many good rational and logical arguments against theism but not one argument in favor of it that doesn't rely on a fallacy or assumption.
* There are so many Gods put forth by thousands of religions that no one could ever be certain of picking the correct one, assuming that one exists.
* Prayer is totally subjective and cannot be shown to have any more efficacy than pure chance.
* There is no discernable difference between believing in God and having an imaginary friend.
* People generally rely on facts and evidence in every human endeavor except religion.
* Unequivocal miracles do not occur.
* God supposedly speaks directly to the human spirit. This must be, at least partly, the same concept as mind. People who receive messages in their minds are invariably delusional.
* There is no positive correlation between belief in God and being a moral person.
* Populations that are predominantly theistic are almost invariably poor and undereducated. The converse is almost invariably true of populations that are predominantly atheistic.
* Populations that are predominantly theistic almost invariably have higher general crime rates, higher violent crime rates, higher murder rates, higher infant mortality rates, more disease and starvation as well as inadequate healthcare. The converse is almost invariably true of populations that are predominantly atheistic.
* Belief in religion has spawned uncounted cults that draw people in by appealing to the concept of faith without proof and the promise of prophets to come. Some examples are: Jim Jones and the People's Temple, David Koresh and the Branch Davidians, Marshal Applewhite and Heaven's Gate. These groups had religious followers who were convinced to brutalize, mutilate and kill themselves and their children on the basis of this kind of blind faith.
* Religion has an extremely violent history that includes such things as crusades, inquisitions, witch hunts, genocide, terrorism and holy war. Untold millions have died in the name of religious icons and for religious beliefs.
* Religions have a long history of misogyny.
* Religion can be and has been used to support the concept of slavery.
* Religious dogma is practically immune to the incorporation of new facts. The best it can do is strained reinterpretation.
* The argument that God cannot be proven not to exist is irrelevant when one considers that to do so requires that the concept of a supernatural God be intelligible and coherent, which it is not.
* There is a well known argument commonly called "The Problem of Evil". It basically says that if an omnipotent and omnibenevolent God exists, unnecessary or gratuitous evil would not exist in the world. Thus if God sees this type of evil and does nothing he is either not omnibenevolent because he doesn't care or not omnipotent because he is unable to stop it. There are many counter-arguments that have been used. However the only one that really could defeat the Problem of Evil is if one says that we cannot apply human standards to decide what is or is not gratuitous evil. This may well be true, but that argument renders God unintelligible and meaningless to humans. Either way, the concept of God seems to be highly doubtful.
* Theists claim that God has given humans free will. However, this free will is anything but free. The choices are forced on pain of death and eternal suffering. It is equivalent to having a slave and saying something like: "I grant you your freedom to leave at any time. But if you do, I will torture you mercilessly and kill you as slowly as possible.""
Thanks again to Mr Friday.