Widespread belief in different gods; an apparent inability by the god(s) to reveal themselves in a way which convinces people who do not already believe, scriptures which are said to be inspired but are open to many interpretations, religious organisations that prove to be no better, even on the issues they hold most dear, than secular organisations, constant redefinition of god(s) to accommodate the advance of science and other knowledge; a failure of believers to identify a mechanism by which the alleged spirit makes contact with the physical brains of people to create faith; the fact that if there is a god(s), god must condone the suffering of innocent animals… But actually I don’t think all that disproves the existence of god(s) - just makes it most unlikely.