I am not a doctor so I am not 100% sure im dealing with a schizophrenic but here is the situation. I like to play pickup basketball and this guy has been showing up to the park lately and been acting quite strange. He always challenges me to play 1v1s and ill usually play with him. When we play he says very very strange things and talks about all of the people around us when there is noone there. When people do walk by he will usually harass them with words that dont quite make sense. He quotes the bible quite often when were playing and generally does things that make me feel very uncomfortable.  I have been very careful with my words around him because I fear if he turns violent he will literally murder me. He is a massive man at around 6 5 and 250 pounds solid muscle. Today when we were playing he started losing pretty bad and I could tell it was bothering him. He was becoming quite agressive with and i calmly asked him to please respect me and reiterated it was for fun. He really didnt seem to show emotion and kept asking me questions I couldnt even make sense off. The next play I let him get the ball and he just ran up the court and smashed the ball into my stomach. I told him that wasnt nice and I wont play anymore if he acts like that. Again- he was saying strange things and I decided that for my own safety it was time to leave. My question is- how am I supposed to deal with something like this. Im worried that hes going to hurt one of the many children that show up to the park. I am 32 years old and am at a loss. I really dont want to stop playing basketball at my favorite park- thanks.