Atheists are just the other side of the coin from religion, they KNOW there is no god and nothing you say matters. They can't prove it, but they have absolute faith and will fight you every step of the way because their dogma demands it.
Agnostics are more the chill ones. They know they can't prove if there is or isn't, they just know religion isn't for them.
Nothing more cringe than listening to either gender talk about the opposite gender as if they have solved the puzzle.