1. Total size of the universe. 2. How many universes are there. 3. Life after death. 4. Why is someone born rich and other born as poor. 5. Why do we die. 6. Why innocent people are killed. 7. Why some children die when they even did not live their life properly.
Theists can answer all these questions. The Vedic scriptures tell us everything which we see, perceive, we have discovered and invented PLUS Vedic scriptures also tell us the things beyond our perception.
Just because we cannot see God with our materialistic imperfect eyes, so the best policy is to deny His existence.
JGN, a person in USA has not seen or met you. So he denies ur existence. Does this mean that you cease to exist? But if the person wants to meet u, he will have to fly all the way to the place where u live and then meet u. Similarly, there is a specific process and by following that path we can also see and meet God. But by denying His existence, we will never even attempt to start the process.