" Philip was downright and intolerant, and he could not understand that a man might sincerely say things as a clergyman which he never acted up to as a man. "

I am famililar with this word only as an intensifier with another adjective. I have no idea what it means in this
sentence.

It's not a word I would use myself in this sense but I am familiar with it as meaning of very decided views.

Bingley