Is christianity demonic?

When ex new agers become Christian, many of them seem to report an increase in demonic experiences. They say it's the demon putting up a fight for their soul etc, but shouldn't it decrease if you enter the protection of Jesus Christ according to them? Or maybe that's me assuming it should be so easy/black and white.

Pair that with a video I watched, speculating about sacrificial things going on under the vatican, and the person was saying it seems more like there are different gods you can go under, so it's like christ vs satan and there's a war between these two witchcraft cults or whatever. As opposed to christianity being this thing thats separate from witchcraft.

I am only asking this as a question, not to insult defame or disrespect, because I am trying to find what I believe. This question arose for me, and if there is a God who created us then best place to write the bible would be inside us surely? So I look for answers to some of the questions that arise in me.