Lapistia

Are other religions even needed besides Elulu-Suen, Iris, Gavellus, Aldis, and Zetsumeya with Saya?

Of course, at least Ain is needed for Judeirn.

But what's the point of the penalty then?

Well, such a "resurrection" won't help this character win battles. But if the allies still win, they can revive their friend, so he won't be disposable. It seems logical.