The most important factor here is to get the person on medication. That is the primary way that the thinking will improve. It can be hard to convince someone, but even getting them to a community based clinic can help. Do not argue regarding their thought process. Try to “join their world” and find a way within that to motivate them toward the end goal. In the meantime, getting support for yourself is important. Dealing with someone who is paranoid can be exhausting.