More from Martin Luther's "Credo of Belief" (1522):

"I believe that in this community (or Christianity) all things are in common, and one's own goods belong to others and no one has anything of his own. Therefore, all prayers and good works of the whole community come to help and must stand by and strengthen me and each individual believer at all times in life and death, and so each one bears another's burdens as St. Paul teaches.

I believe that there is in this community and nowhere else the forgiveness of sin, and that outside of it there is no good work (no matter how much or great) that can help to make possible the forgiveness of sin. But in it nothing can harm (no matter how much, great or often one may sin) the forgiveness of sin, which remains where and as long as this one community remains, to which Christ gave the keys."