Exactly. Penance is a condition of the heart, not actions, and NOT, IMO, suffering. Except maybe for regret and remorse for sins committed.
As for Catholic doctrine, why would it offend me? I don’t get offended if a Muslim tells me Allah will throw me into Hell if I don’t accept their religion.
I do get offended if they were to try to force me to do so, or pay an extra tax for the privilige of not doing so.
It seems to me that if you have confidence that you are right with God, what others say doesn’t really matter, so why get offended. A lot of people don’t think that way, though.
That being said, there was nothing in your quote that I could not agree with, except that litle bit about mortification. I don’t exactly know what that means, but it doesn’t sound good, if I remember the little Latin that I had 50 years ago.
And I don't know either, but a couple of folks reacted rather negatively to my posts on this thread. Oh well, can't please everyone, I guess.
Mortification is simply self-denial in pursuit of a greater closeness to God. It is avoidance of those things which lead to sin, a renunciation of one's sinful past life.
"If you live after the flesh", says the apostle, "you shall die, but if through the spirit you mortify the deeds of the flesh, you shall live" (Romans 8:13; cf. also Colossians 3:5, and Galatians 5:24). Nothing more gruesome than that. ;0)