Apologies to my religious friends, but this was too funny.
Since my teen-age years I've used the following to explain how I arrived that there is no God.
A is A. (A being defined as EVERYTHING.)
A has always existed. (Inconceivable)
A comes from nothing. (Impossible)
Following the dictum of the great 19th C philosopher Sir Arthur Conan Doyle "once you've eliminated the impossible, whatever remains, no matter how improbable, must be the truth."
Since A coming from nothing is impossible therefore A has always existed.