Send him this without explanation.
Report back results.
Sounds like something out of A Scanner Darkly.
I've never really seen anyone be able to talk someone else out of having paranoid delusions. Do you need to be living with this guy?
I have two roommates because I'm a broke millennial and cost of living is cheaper when you share rent and utilities. So yes, I kind of do need to live with other people.
Do you need to be living with him, that's what I'm asking. Who has the place and bills in their name and is there anyone who you could move in with or move into his spot with 30 days notice?
this is what weed does to people. Can you try to get a new roommate?
I would let him explain his worries in detail, then point out that there is no reason for me to plot against him and no profit and finally would offer to go out of his way as much as possible, if that makes him happy (passive aggressive threat). He might overthink his behavior, depending on how close you are.
If he is smoking heavily every day, that could really be a cause. I remember fleeing to the bathroom when the door bell rang in my green days.
For some people, weed can trigger schizoid paranoia and even full blown schizophrenia.
He has simply smoked too much weed and needs medical attention. If you can't get him to care otherwise, you should actually snitch.
This type of stuff can ruin lives, and I've seen it happen many times in my own family.