From my experience dealing with deities, I wouldn't put it past them that this world is a creation of one of them. And to which they bring people from other worlds since the deities of those won't let them meddle with us in our homelands. Consider it their own private playground, in which those Malnosso may be working for them or not.

[Ikki merely shrugs at the last part, at any rate that they are the ones responsible of them being inside that barrier is pretty much sure. At least as far as he's concerned. And to be fooled or controlled doesn't exclude one from their sins, that's something the Gold Saints knew very well and the reason why so many of them gave up their lives upon realizing that they had been fooled and had been following a fake Pope who had tried to kill their Goddess.]