Evil god or not claiming that all humans desire imortality is too much of a misanthropist slander to be left standing. Is she a god in the first place, seems a little lacking in the knoledge portion of the deal.
Anyway the Demon Lord and the Hero teaming up to confront the God who forced their fate on them. I wonder who came up with that, since I doubt this series stole from Sekai Maou (not that it's wrong to steal from Sekai Maou, it's already finished and it's great), both must have been inspired by something older.