Is believing in a god a selfish act?

Imo every act is selfish as we all want to gain something from it, no act is selfless as we get something from it be a good feeling or a possessive object. People believe in god in order to get into heaven and be better people, imo this is done so they get the best end of it and they get 'true enlightenment' therefore i feel that there are no selfless acts.