Why do SOME athiest get upset with anything that deals with religion and try to take it out of everything?

Aren't athiest religious in a sense that they choose to believe in something when they believe in nothing? They BELIEVE that there is no God and no need for religion but isn't belief in SOMETHING a part of religion? I once met this guy who was athiest and if you mearly mentioned anything about religion he would try to discredit you and tell you the reasons why you should NOT believe in God or any religion. However, I did not sit there and try to beat into his head the reasons why he should believe. I respected his views in why he believed there is no God but he had no right to question my beliefs and question the reasons why I believed if I did not question his. Why is it so wrong for me to believe in a positive entity that I find inspirational and motivating. I turn to prayer for its healing powers and for the healing powers of others. Why must you attack my beliefs if I respect yours?