If Caucasians count as white, then Iranians are white. A lot of Iranians are also religious and right wing too. The average Republican and the average Iranian would agree with each other on nearly everything if they could somehow have a conversation without divulging their country, clothes, and specific God.
"White" is whatever the racists want to establish as the civilized norm which needs to defend itself against the non-white barbarians.
Arguing with "caucasians are from Caucasia" is stooping to the racist's level of discourse. You shouldn't argue with Nazis about the nature of "Aryans", either.