The Protestant principle testifies to God’s sovereignty against human endeavors.  Continually Protestants remind us not to absolute the relative.  God is beyond nature and history.  For many Protestants, the Bible is the ultimate source of truth, the living word of God.  On the other hand, dogma, sacraments, and church are at the heart of Catholic belief.  Protestants do not grant papal infallibility, preferring to rely on the corrections of the Holy Spirit.  You need to continually protest against something.