The following is taken from Martin Luther’s The Babylonian Captivity of the Church. It is in part a response to a statement by Jerome, the Latin Father, that “penitence” is “the second plank after shipwreck.”
When the children of Israel turned to penitence, they remembered, first of all, their exodus from Egypt; and in remembering this they returned to the God who had led them out. Moses constantly impressed this memory and this leadership on them, as David did the same. But how much more ought we to be mindful of our exodus from our Egypt, and, with that in mind, to return to Him who led us out through the baptism of rebirth which we are commanded to remember for this very purpose! This can be done most appropriately in the sacrament of bread and wine. Formerly the three sacraments of penitence, baptism and the Lord’s Supper, were celebrated with the same end; and they supplemented one another. Thus we read of a holy virgin, who, as often as she suffered temptation, made her baptism her sole defense; she said briefly, “I am a Christian.” The enemy immediately perceived the power of baptism and of a faith which clings to the truth of a promise-keeping God, and fled from her.
In this way, you will see how rich a Christian is, i.e., one who has been baptized. Even if he wished, he could not lose his salvation however often he sinned, save only if he refused to believe. No sins have it in their power to damn him, but only unbelief. If his faith relies on the divine promise made at baptism, all things else are embraced by that same faith, nay by the truth of God; because He cannot deny Himself, if you confess Him and continue to cling to His promise. But “contrition” and “confession of sin” followed by “satisfaction,” and all the other devices thought out by men, will desert you suddenly and leave you in distress, if you forget this divine truth and batten upon those things. Whatever is done apart from faith in the truth of God, is vanity of vanities and vexation of spirit.
Similarly, you will see how dangerous, indeed false, it is to imagine that penitence is a plank to which you can cling after shipwreck; and how pernicious is the error of supposing that the power of baptism is annulled by sin, and that even this ship is dashed in pieces. Nay, that one ship remains, solid and indestructible, and its timbers will never be broken to pieces. All who voyage in it are traveling to the haven of salvation, namely, the divine truth promised in the sacraments. True, it often happens that many people foolishly leap out of the ship into the sea, and perish. These are they who abandon faith in the promise and plunge themselves in sin. But the ship itself survives and, being seaworthy, continues on its course. If any one, by some gracious gift, is able to return to the ship, he is carried into life not by some plank, but by the well-found ship itself. One who returns to the abiding and enduring promise of God through faith is such a man. On this account, Peter, in II Peter 1, rebukes those who sin, because they are forgetful of the time when they were cleansed from their former sins; doubtless reproving them for their ingratitude after accepting baptism, and for their disloyal impiety.