How can you tell which gods are real or fake?

Their is only one GOD no matter the religion nor thy name [GOD Allah Zeus Ect.] we all pray to the same GOD don't let religion beliefs interfere with your relationship now in Greek mythology there are differences but if I had to says there is only one GOD it would be Zeus whitch is said to be GOD of the GODS

Answer:

Ask God to reveal to you who He is. Seriously. If you want the correct answer, then ask the Big Man Himself. He obviously knows who He is.

And if He never discloses Himself to you, then He either doesn't exist or He doesn't see it as important for you to know.

Answer:

There is no scientifically supportable evidence for any god. By this logic there are no gods so all claim to have a "god" are fake. Then again, if a god can be tested for (made to jump through some hoop to prove its existence) then you'd be calling the shots not him, and he would be demonstrably less of a god than you are.