Oh
@UncleDiLF you poor quasi-sentient sod...
I don't just deny the existence of your god.
I deny the existence of all of them, ever.
They're all quite obviously figments of men and women's imaginations.
You're almost as much of an atheist as I am, ya know, unless you happen to believe in everything from zoroastrianism to L. Ron Hubbard's space fairy.
I just take it one step farther.
God probably is out there, a part of the universe, maybe more. A simple experiment to prove His "is-ness," is to suppose that He might be out there, and then ask Him to make you believe in Him. If he is out there, He might respond to your prayer by giving you a gift of faith or belief in Him. So, if this happens, this confirms the idea that He is there.
Now, you might be tempted to doubt, ad hoc, this confirmation as some sort of self-delusion. So, you will have to use your newly acquired faith to do some miracles that confirm that something has happened that you were not in control of. Better, in fact, plan on this. Pick out some miracles you want to work with faith ahead of time, things that would be good for others.
If it doesn't happen, well, maybe He is not out there. Or, maybe He is there, but did not want to give you this gift of faith. These alternatives can be separated by asking Him why he did not give you faith, by asking Him for what you might do to prepare yourself to receive. If, with this request made, you sincerely believe that every thing you might have done to qualify yourself to get belief from God is done, and still He does not give you faith, then, from your perspective, He probably does not exist.
But, you are not entirely at the end of your search. In the bible, there is something called "taking the kingdom of God by violence" or force. If God exists, but is hiding Himself from you, you can "prove" Him by "buying the truth," by doing a tithing experiment, as outlined in Malachi. That is, whether or not He gives you a special teaching or gift in response to your request, you might reason that since He and His followers have gone to such great lengths to get a bible available to you, with all it's specific instructions for finding Him, and proving Him, maybe He is waiting for you to do all the stuff written there, before he does any further gifting. "Knock," in other words. Hammer away, make a nuisance of yourself.
It seems to me that a completely clear conscience on this matter requires enough effort on our parts, that we are pretty clear that we have done all we could to get God to respond in a reasonable way. This, alas, cannot be limited to reasoning on our part, for the God we are looking for has made it clear that he is much more into evidence, and "asking, seeking, knocking," then any approach which depends on our understanding. He limits understanding and logic to supportative roles only, and appears to dread the idea of having to invite some "deep thinker" into His everlasting dinner party. Or maybe that is just me.