For thousands of years, theists have used their versions of God to explain what they cannot explain. The beginning of the universe? I can't explain it, but I also do not accept the theists' explanation.
I'm not against anyone's religion. I just don't want any part of it. See, there's that whole lack of belief; I don't hold a negative position. I don't deny the existence of a God, for to deny such a thing would mean that I have knowledge of a God that I am being asked to affirm. I don't.
I will, however, stand up for secularism in government, as I do believe that the separation of church and state is necessary for a truly free society. As far as I'm concerned, you are free to practice religion as you see fit -- or none at all -- as long as it does not infringe upon my right to live the life I choose, which is that of an atheist.