When was evil created?

[Neo-Scholastic]

That is twice now that the xtians have mentioned other documentation than the bible.

Both Jesus and Peter quote from sources not found in the canon. Much has been lost.

In any case, I think it is kind of odd that the xtians would have to go outside of their holy book to answer these questions.

The canonical Bible contains all the essentials of the faith. I contend that even if the only surviving text was the Gospel according to John, it would contain everything needed for a saving faith. Everything else is gravy.

If angels did, indeed, come from man, then how is the evil (serpent) in the garden explained?

The evil was not int the snake. It was in the original community of believers that relied on external knowledge of good and evil based on their own earthly senses. The serpent represents their own reasoning that that lead to the fall.