Agnostic = No way to know know if there is a god or not
Atheism = There is no god

What pushed me from Agnosticism to Atheism was a simple thought experiment. I asked myself "Do I believe in [fairies, minotaurs, etc.)]?". The answer was no. Surely I can't know for a fact that they do not exist (agnosticism) but having seen 0 evidence means that I place the probability of it existing so low that for all intents in purposes I do not believe they exist (atheism).