A gross misinterpretation if there ever was one.
The Greek word that the Catholic church translated *penance* is the word for *repent*, which is not at all the same thing.
http://biblehub.com/text/acts/2-38.htm
True, penance is a work, but it is not what Peter was telling others to do. Works don't save.
“gross misinterpretation...”
Absolutely not. The Douay Rehiems bible is the closest translation to the original Latin and Greek that is out there. Later “bibles” contain modern error. The Douay Rheims is base 100% on the original Latin and Greek vulgate translated by St. Jerome himself.
“Works don’t save”
Christ saves, works are required to cooperate with the saving grace of Christ. Faith without works is dead, so if there are no works, a person’s faith is dead.