Found this article posted to the Devoted Geek Life Facebook page:
Superman's New Weakness Is the Power of Prayer
Apparently, Superman and his son, Jonathan, fly to another planet to save it from destruction, but all the planet's inhabitants worship a deity called Dhermet, and they believe that their destruction is a good thing, so they don't want Superman to help. Their prayers to their god actually affect Superman's powers. Superman's torn, because even though they don't want him saving them, he doesn't want them to end up like Krypton.
So we know Superman is vulnerable to magic like Mr. Mxyzptlk's and Black Adam's, but apparently, devout faith can also do him damage.
Kinda weird. The story was written by James Robinson, who;'s famous for his run on Starman.