As'salamu Alaikum dear brothers,
Not trying to give a superficial answer, but really using these God-rejectors' logic, then it is impossible for us also to exist. Yet, we are! The best these people can give from "reasoning" about GOD Almighty not existing is things such as the following:
1- Which came first, the egg or the chicken?
Answer: How about pondering upon how did they BOTH came to existence?
2- How can GOD not have a begining?
Answer: How about pondering upon where were you 2 years before you were born? And how SUDDENLY you came to existence into this flesh and blood world? Could you answer that?
3- How can humans not have originally came from animals?
Answer: Instead of limiting your thinking into things of this kind, how about pondering upon how the atoms, that make up every physical thing, came to existence? Who made them?
Their usual counter answer: They came from the unknown that we can't currently explain.
Counter answer to that: We call this "unknown" GOD Almighty, and the proof for this is the fact that every physical thing in the Universe of ours (from celestial bodies to physical creatures) was clearly engineered. We're not just blogs of physical forms. We have preceise things for precise functionalities. Example: Our hands wouldn't be much if they didn't have the 10 fingers. We couldn't do much with them.
Their usual counter answer: This evolution, and we have evolved. We weren't created with two arms and 10 fingers. Plus some of us have more than 10 fingers through what is known as birth deformities.
Counter answer to that: Again, everything comes down to the Atom, and you can't explain how it came to existence. So at best, you have no answers. You're only speculating. And we have ample reasons to believe that we didn't evolve from animals. Our bodies were different (we were larger) and went through changes (
Islam supports this), but none of this disproves GOD Almighty's existence, nor does it explain how the atom came to existence. So again, the best you can do is speculate and nothing more.
Their usual counter answer to that: You're a dumb Muslim fool!
Counter answer to that: Well you're a dumb atheist moron!
I hope this helps, insha'Allah.
Take care,
Osama Abdallah