The argument, I think, is that the Bible is Anti-Magical. No Fairies, or other magical creatures are allowed. In fact, there is a volume of the manga "The Ancient Magus' Bride" where the Fairie Queen Titania banishes a Catholic Priest from her kingdom. I think it was volume 3. It was pretty badass. To go even further, Magic in general is banned in the Bible for use by humans. Some modern Witches believe that this was put in during the King James Version of the Bible to take Magic away from the poor as a way of subjugating them and taking away any kind of power that might pose a threat to the Monarchy. This all points to Pokemon having powers as both a revival of Magical Creatures and Humans in control of Magical Power. Both of which are threatening to a Christian Worldview. You might, a reasonable person, ground in reality, say that "Magic doesn't exist. It's a fantasy." Well when the advent of Christianity spread across the world, it didn't happen in a nice and polite way. People were still savage, and so was their way of spreading new ideas. The Church was no exception to this, and anyone found to be practicing Magic was tortured or outright killed. Many traditions of Magic had to go underground and survived in secret within families down the generations, but the lion's share of Magic in General Human Civilization was wiped out. Science and Technology replaced Magic under the watchful eyes of the Church, but not without a lot of intervention that slowed progress down so much that we are only recently starting to advance at the proper speed. History is full of accounts of Magical Creatures and Magic-using humans. The Old Gods become the New Demons. Modern Magic Users have only scraps of knowledge compared to what used to exist long ago, and the revival is in it's infancy. So it will take a long time for Magic to come back. They kind of make a projection of this idea in the cartoon "Adventure Time" where science has been driven undergound from almost complete destruction and Magic becomes the overgrowth from neglect that permeates and forms the basis of reality once again. Christians know the danger of this overgrowth, so they spread weed-killer on the sidewalk, figuratively speaking. Hence the Anti=Pokemon sentiment.