I'm not sure why you find this so hard. Everyone can list propositions they believe and ones they don't believe. As
@mikkel_the_dane said at the start, an atheist is one who doesn't believe in deities. That tells you almost nothing about what else they believe or don't believe. Some may be physicalists and have a worldview in which only those things for which there is objective evidence are real. Others may observe the religions of the world and their commonalities and come to conclusion they are the result of human psychology rather than being true. Others again may simply see no reason to trouble themselves with the issue at all. (I knew someone like that at university.) But they may believe plenty of other things of course, from political ideologies to the effectiveness of acupuncture. There's nothing about atheism that implies any particularly sceptical cast of mind, though some indeed are natural sceptics.