Who Am I?

This is a little game I am introducing to this blog. It's called Who Am I? The name basically says it all. I will give some clues on a saint, Biblical figure, bishop, priest, or someone otherwise famous within Catholicism, and you must guess who it is. The answer will appear the following day.

Post your response in the comments. Make this a real challenge and do not research the answer. If you get it wrong, that's ok, don't feel bad, and if you're not sure, make a guess anyway.

WHO AM I:
Not quite 50 at the time of my death
My philosophy has shaped the West
I was a member of the OP
and I'm in a group of thirty three