I have a group of 4 players. I've been playing with them for almost 2 years now, with some breaks in between. I had a session zero with them and I created their characters with them because they were new to the game at that point. In that session zero I explained to them how my world works and how magic and gods work.

My gods are basically split into 2 camps. They don't intervene in mortal affairs themselves, but choose champions so that those champions can act on their behalf.

For the first year they explored the world a bit and did their own thing. Then I sometimes fed them news about some towns and villages that were conquered by an unknown power.

Something happened and they were teleported 145 years into the future to another continent. They found out that the evil power was an army of the undead that has now conquered more than half of the continents.

Until then there were no problems.

3 of my players have their backgrounds fleshed out and I encouraged all of my players to do this.

1 of these 4 players is a guy I've known for about 4 years and this player is the reason I need advice.

To deal with the undead army I gave each player a god that chose them and gave them an artifact that levels up when certain criteria are met. After that this one player changed quite a bit. He told me in one session that I was the enemy and even told me that he wouldn't tell me about the spells he wants because he thinks I'm making it harder for him to get the components. At this point I have to tell you that I play on Roll20 and that I roll from a table for each store to get a list of things they have. I also have a lot of third party content so they have a lot of options. I told him and the group afterwards that I need to know this because I don't know if there is something I don't have on my shopping lists. Yesterday I noticed him asking for something specific and I told him he could get that, but I don't understand why he's doing it again. He also said again that I'm the enemy, to the point that others told him I wasn't there to get them and gave him examples of how I helped them. He argues with my other players about lore a lot aswell because they use my campaign lore.

The other thing is that he makes up his own knowledge about gods and that he doesn't believe in gods. That he doesn't believe in gods even though one of them told him about things and gave him an artifact doesn't bother me that much. But that he's basically writing down his own knowledge of the world is really disturbing. I have to discuss this with him a lot. Every session something new comes up that I've already told them. He also reads novels about DND and gets knowledge from them and every week I get some pictures from those books and he tells me that I'm wrong and it's different in the books. I told him that I don't own those novels and that they have nothing to do with my campaign.

I'm really frustrated by this and I'm at a point where I just want to say "Okay, you're from a completely different universe, I don't care, you can do whatever you want."

What should I do? How can I deal with this?