The entire obedience of Christ's entire person is credited to us for righteousness...

Even if Christ had been conceived and born without sin by the Holy Spirit and had fulfilled all righteousness in His human nature alone, and yet had not been true and eternal God, this obedience and suffering of His human nature could not be credited to us for righteousness.  Also, if God's Son had not become man, the divine nature alone could not be our righteousness.  Therefore, we believe, teach, and confess that the entire obedience of Christ's entire person (which He has offered to the Father for us, even to His most humiliating death on the cross) is credited to us for righteousness.  For the human nature alone, without the divine, could not by obedience or suffering make satisfaction to eternal, almighty God for the sins of all the world.  However, the divinity alone, without the humanity, could not mediate between God and us.
~BOC, FSD, III, 56

Forgiveness comes through grace, without any work, merit, or worthiness of ours preceding, present, or following...

We believe, teach, and confess what our righteousness before God is this:  God forgives our sins out of pure grace, without any work, merit, or worthiness of ours preceding, present, or following.  He presents and credits to us the righteousness of Christ's obedience.  Because of this righteousness, we are received into grace by God and regarded as righteous.

We believe, teach, and confess that faith alone is the means and instrument through which we lay hold of Christ.  So in Christ we lay hold of that righteousness that benefits us before God, for whose sake this faith is credited to us for righteousness.

We believe, teach and confess that this faith is not a bare knowledge of Christ' history, but it is God's gift.  By this gift we come to the right knowledge of Christ as our Redeemer in the Word of the Gospel. And we trust in Him that for the sake of His obedience alone we have--by grace--the forgiveness of sins and are regarded as holy and righteous before God the Father and are eternally saved.
~BOC, FE, III, 4-6

We must always run back to the promise...

Paul knows that through faith he is counted righteous for Christ's sake, according to the passage "Blessed is the one whose transgression is forgiven" (Psalm 32:1).  But this forgiveness is always received through faith.  Likewise, the credit for the righteousness of the Gospel comes from the promise.  Therefore, it is always received through faith.  It must always be regarded as certain that we are counted righteous through faith for Christ's sake.  If the regenerate afterward think that they will be accepted because of the the fulfilling of the Law, when would a conscience be certain that it pleased God?  We never satisfy the Law!  So we must always run back to the promise.  Our infirmity must be recognized in this manner.
~BOC, AP, V (III), 42-44

None is righteous, not one as all are lost apart from Christ...

Now some did not believe themselves guilty of actual sins in thought, word, and deeds.  I, and people like me in monasteries and religious communities, wanted to be monks and priests.  We fought against evil thought by doing such things as fasting, staying awake, praying, saying Mass, wearing coarse garments, and sleeping on hard beds.  In total sincerity and with great effort, we wanted to be holy.  Yet the heredity, inborn evil sometimes came out in sleep, as happens (St. Augustine and St. Jerome, among others, also confess this).  Still, each one held the other in high esteem.  According to our teaching, some monks were regarded as holy, without sin, and full of good works.  Also, since we had more good works that we needed to get to heaven, we could communicate and sell our good works to others.  This is actually true.  Seals, letters, and examples are at hand to prove that this happened.

These holy ones did not need repentance.  What would they repent of, since they had not indulged their wicked thoughts?  What would they confess about words they never said?  What should they render satisfaction for, since they were so guiltless that they could even sell their extra righteousness to poor sinners?  In the time of Christ, the Pharisees and scribes were these kinds of saints.

But here comes the fiery anger of St John, the true preacher of repentance.  With one bolt of lightning, he hurls together both those selling and those buying works.  He says:"Repent!" (Matthew 3:2).

John says, "Repent, both of you. You also penitents and false saints, both of you need the forgiveness of sins.  Neither of you know what sin really is.  Much less your duty to repent of it and shun it.  For no one of you is good.  You are full of unbelief, stupidity, and ignorance of God and God's will.  But He is present here, of whose "fullness we have all received, grace upon grace" (John 1:16).  Without Him, no one can be righteous before God.  Therefore, if you want to repent, repent rightly.  Your works of penance will accomplish nothing.  As for you hypocrites, who do not need repentance, you serpents' brood, who has assured you that you will escape the wrath to come and other judgments?" (Matthew 3:7; Luke 3:7).

In the same way Paul also preaches, "None is righteous, no, not one; no one understands; no one seeks for God.  All have turned aside; together they have become worthless; no one does good, not even one" (Romans 3:10-12).  And God now "commands all people everywhere to repent" (Acts 17:30).  "All people," He says. No one is an exception who is a human being.  This repentance teaches us to discern sin:  We are completely lost; there is nothing good in us from head to foot; and we must become absolutely new and different people.
~BOC, SA, III, III, 28-35

Faith means not merely knowledge of, but also belief in the purpose of history...

Faith means not only a knowledge of the history, but the kind of faith that believes in the promise.  Paul plainly testifies about this when he says in Romans 4:16, "That is why it depends on faith, in order that the promise may rest on grace and be guaranteed."  He judges that the promise cannot be received unless it come through faith. Therefore, he puts them together as things that belong to one another.  He connects the promise and faith.  It will be easy to decide what faith is if we consider the Creed, where this article certainly stands: the forgiveness of sins.  It is not enough to believe that Christ was born, suffered, was raised again, unless we add also this article, which is the purpose of the history: the forgiveness of sins. I mean that because of Christ, and not become of our merits, forgiveness of sins is given to us. For what need was there that Christ was given for our sins if our merits can make satisfaction for our sins?
~BOC, AP, IV (II), 50-52