Islam and atheism are two different things. It's like talking about two opposite things, because Islam is a religion that believes in the existence of God, while atheism is a form of belief that God does not exist. Islam is one of the most practiced religion in the world. Prophet Muhammad is popularly known to be the founder of the religion, while atheism is just a conviction of the mind to think that God does not exist.
Those who think God does not exist are called atheists. Another difference is that, while Islam uses the Quran as a manual for guidance and protection, atheism does not have any form of manual or book. Most atheists are people who are rich intellectually e.g scientists, philosophers, etc. They always have a kind of belief that there can't be anything called God. Islam believes that God is the creator of the whole universe, and He should be worshipped accordingly.