Complex sentence: A 501 (c) (3) non-profit organization that seeks to promote the positive contributions of atheism and to maintain the separation of state and church, they are affiliated with Atheist Alliance International, and the American Atheists.
Split into simpler sentences: A 501 (c) (3) non-profit organization that seeks to promote the positive contributions of atheism and to maintain the separation of state and church. They are affiliated with Atheist Alliance International, and the American Atheists.