In the Christian worldview the concept of human includes an immortal soul, which is created by God and has free will. Free will - a person's ability to be cause for their actions and decisions himself. Possessing free will, a person can make an responsible choice between good and evil. In fact, without the recognition of this ability of the person the religion makes no sense.
The atheistic conception of the world offers that there is no God, gods, angels, spirits, souls, etc. For the consistent and uncompromising atheist only matter is real. Cases where an atheist believes in something spiritual, but does not want to listen to the priests, will not be considered.

Atheists often offer believers to show them God, and then they promise to believe in Him. Let me offer you a way to detect God - He is found by the very fact of your existence. You are the immortal soul, created by God, and a material body. The fact that you have free will, is evidence of the creation of your by God. It is with this reality you they  trying to argue, calling himself an atheist.