One of the greatest secrets made known to me about Allah is that i cannot know Him nor reach Him but He knows me and reach me everyday through His Signs.
This is considered a secret because we cannot really go around talking about it, or else we miss the whole point about submission to Him. It is both a knowledge of the secrets and an amal of practice. His secrets are made known to whom He so chooses.
You cannot prove His existence nor disprove Him as Allah by definition has no definition - cannot smell, touch, feel, locate, etc. We know Him only via dalil naqlia which is His own ayats i.e. starting from His revealed scriptures such as the Quran. Many tried but are lost because of the Satanic syndrome - wrongful pride, takabur, anger, ego, holier than thou, etc.
So in order to know him firstly is to accept your own condition He puts you in and be patient. Secondly make prayer to Allah so that He grants you this knowledge. Thirdly go back to First rule.
It is always Allah's actions in the end.
But it is dead simple. But you end up making it complicated for yourself. Do not be another priest.
This is a truth that is both easy and difficult but it is in line with what older books sent before this one.