So, you're a hardcore atheist, and you firmly stand by that belief. You don't believe in fairy tales, magic or the Sky Queen bullshit. Another day, another internet argument with some religious hippie, but this time you're fed up; you are going to once and for all disprove this non-sense.
So you sit down and study biology and medicine exhaustively, no soul there; check.
So you sit down and study physics to remove all these uncertainty principles.
And on and on you go, discovering indisputable evidence and theories all throughout all branches of hard science. Because of your quest, your knowledge so far allows you to extend your life far beyond the span of any normal man. Over the years your meanderings through technology allow you to sharpen your wit and increase your memory, to hold and contemplate all that you have learned.
Even further along you discover the secrets of time and space.
To get all the answers you need to travel to the very ends of the universe and gaze upon the very moment of creation. Finally after eons of investigation, you have all the evidence collected and have formulated and proven a theories so beautiful they might just as well be a works of art.
As you return to earth, you climb a hill to address the people below and finally reveal to them the truth of religion.
As you start out "I have conclusive evidence that there is no such thing as an immortal and all-knowing being that ... "
That's when the irony strikes you and you raise your fist against the sky. "You tricked me you bitch!" you cry out.
After your anger subsides, you shave your head and go bake a cake. It sounds like just about as pleasant a thing to do to pass the time as any a thing right now, and it smells pleasantly to boot.