Key Difference: Atheism and Theism both deal with religion and the existence of God. The primary difference between Atheism and Theism is the fact that theism is the belief in the existence of God, whereas Atheism is the belief in the non-existence of God.

Religion and belief is a personal matter, it is said that what a person believes is between him and his God. However, the matters of religion are rarely left also, hence the existence of God, his role in creation and in everyday life, as well as what a person believes is all subject to comment and discussion, and that is the least of what can happen. People have found themselves discriminated against and even prosecuted or hunted down based on their religious beliefs.

However, even before one can speak about religion, or rather the various different religions, it should be noted that all religions have one thing in common, regardless whether people believe it or not. All religions believe in the existence of God or gods; the God may be singular, as in Christianity or Islam, or multiple as in Hinduism.

The contrast to the existence of God, is the belief that there is no, i.e. no God, benevolent or otherwise exists. This is Atheism. Atheism believes that there is no God or gods, and god certainly did not create the universe, nor does he actively take part in it.