He certainly wasn't Dutch Irish. But there were plenty of Caucasians in the Levant some 2000 years ago. He could have just as easily been Ptolemaic as Ethiopian.
Whatever his skin tone, I think its safe to say he was very tan. But, as a charismatic religious demagogue, there's ample reason to suspect he was good looking by the standards of the era - presumably tall, handsome, smooth spoken, and fairly well-groomed.
That requires you to assume the goals of a Christian nation are out of line with the goals of a Roman Empire. And Emperor Constantine certainly didn't seem to think so.