Some very nasty people sit in the left hand seat. Some sit in the right hand seat, and some work in the cabin. If at all possible they are best avoided. Or if they are unavoidable, bite your tongue. CRM and all that..... But good CRM can be the non avoidance of conflict.
However, if it is a safety issue, then things are more difficult. You have to decide if it needs to go further.
Ask around. If everyone thinks he is an idiot, you will feel much better. If it is just you!! Then it is a personality clash, and just suck it up and move right along.
I do remember flying with a Captain, when I was new to BA, and he was vile to fly with. I hated him. Five years later I flew with him, and he was fun to fly with! He had not changed, I had. As a new pilot I was confused and defensive, and found his dry humour difficult to cope with. Years later, I gave as good as I got, and we got on like a house on fire!
Strange things people.
L337.