[CarolinaGuitarman]

"There is no way that you as an individual are privy to even a small fraction of all human knowledge, so you cannot be certain that there are not other individuals who have knowledge of God."

Not testable knowledge.

"To claim as certain that humanity does not posses this knowledge, or presently have the means of obtaining such information is a claim of omniscience, which is an attribute normally attributed to God, which in this case would be self-refuting, not to mention arrogant."

What evidence is there then?

" Are you assuming that the only way to knowledge is by science and that science is the only valid knowledge?"

Of the natural world yes.

[Diamond]

The proposition that the only way to knowledge is by science or that science constitutes the only valid knowledge is a belief that itself is not derived from science, it is a philosophical statement about science, so it is self-refuting. I presume you mean testable in some scientific, or experimental sense, which excludes a lot of evidence at the outset.

Cordially,