There is a toolkit and a method to prove the existence.
It is called the God Helmet and fMRT.
Put the God Helmet onto the subjects Head, stimulate her/his brain and then make a
fMRT using reaction fluid.
Bam.
https://en.wikipedia.org/wiki/God_helmet
The most interesting thing is: God is proven by electromagnetic radiation.
From philosophical viewpoint the pantheistic approach seems to be the most precise one.
https://en.wikipedia.org/wiki/Pantheism