Atheism is an intellectual position. What reasons do you have for holding that position? Your reasons are based upon logic and/or evidence or lack of it. So, is there any reason/evidence for you holding your position that you defend?
If you say that atheism needs no evidence or reason, then you are holding a position that has no evidence or rational basis? If so, then isn't that simply faith?
If you say that atheism is supported by the lack of evidence for God, then it is only your opinion that there is no evidence. You cannot know all evidence for or against God, therefore you cannot say there is no evidence for God.
If you say that atheism needs no evidence to support it because it is a position about the lack of something, then do you have other positions you hold based upon lack of evidence...like say, screaming blue ants? Do you hold the position that they do not exist or that you lack belief in them, too?
Everything that was brought into existence was caused to exist. Can you have an infinite regression of causes? No, since to get to "now" you'd have to traverse an infinite past. It seems that there must be a single uncaused cause. Why can't that be God?
.Examples of logical absolutes:
Examples of logical absolutes are: something cannot be itself and not itself at the same time (Law of non-contradiction). A thing is what it is (Law of identity). A statement is either true or false (Law of excluded middle). These are simple, absolute logical absolutes
"I lack belief in a God." If you say that atheism is simply lack of belief in a god, then my cat is an atheist the same as the tree outside and the sidewalk out front, since they also lack faith. Therefore, your definition is insufficient.
http://www.carm.org/cut-atheism