This is a question specifically intended for atheists. Answer yes or no when possible; if you cannot, state why clearly.
First, define your position. Are you denying God's existence or just arguing as if He doesn't exist? If you choose not to assert a truth claim, elucidate the significance of your worldview in a truth debate.
Now, explain the initial causes. In your worldview, what is the source of matter, energy, space, time, and the laws that govern them? If you answer “no cause,” explain why brute facts are acceptable for atheism but not for theism. If you answer “infinite regress,” explain why an endless chain of causes is rational while a necessary being is not.