fwiw imo this is an assumption that the Bible does not bear out, even if this is what we are taught. "Scripture" surely had a diff meaning to Paul, and Paul can even be Quoted repeating much that was not within...those parameters, which essentially deny the existence of the many Roman and Greek gods in our Christian "Scripture."
Hades would be a good example I guess, who is "Hades?"
see, he was not invoked out of thin air, nor invented by Paul or any other believer
Hades has been made into Hell for us, but this is surely not what Hades meant to Paul, who was intimately aware of Hades' mythology.
So, should Hades' mythology now be admitted as "Scripture?" tht is up to you, but I suggest that if "...the gates of Hades will not overcome it" is true, a believer should at least be aware of what "the gates of Hades" represents, which is certainly not "Hell."