Discussion of theological differences between Protestants and Catholics seems to get problematic because of it.
A Protestant has to argue his own case, in his own terms, based on his own opinions and beliefs.
When a Catholic challenges those beliefs, it's based on theological opinions handed down from the church - you are essentially arguing someone else's case, in their terms, based on their opinions and beliefs, and they are not here to question about the basis or reasong behind them.
Well actually, I don’t really care as long as people don’t get smarmy or sarcastic. That’s when I get smarmy and sarcastic and it leads me to the near occasion of sin.
Not good for any of us.