It's easy to pick holes in an argument, even if it's a very good argument. So those who don't know God pick at His choice of revelation of himself to this world, first in Word by prophets then by His son in Jesus Christ and now by the news of His Son's actions by the chruch, while from the very beginning, revealing himself through the amazingly complexity and resiliency of the universe around us.
So a good exercise is to think through how you would reveal yourself to your creation of mankind, without forcing them to love you but giving them an option to reject you.
A lot of things can quickly come to mind, write special words with clouds in the sky, but then what language would you pick to write to the whole Earth? Near Eastern Ancient languages, probably not because we would need them interpreted today but then clouds are not that long lived...Take time and think through all your options and realize it must persist though all history and time.
You think about that!