Evil existing is necessary for a test in good and evil. Whether done by humans or natural causes.

Angels were created as perfect servants who obey all commands without free will. Humans were created as the opposite. Those who have free will to perform both good and evil.

It should already know the result of said test, thus making the test itself irrelevant. That’s what omniscience is.

An all-powerful entity is not bound by paradoxes. If that was the case it would end at the https://en.wikipedia.org/wiki/Omnipotence_paradox which is even more extreme than the free-will paradox for which some explanations can be thought of.