To deny that faith justifies teaches nothing but the Law, setting aside both Christ and the Gospel...

... Just as it is necessary to keep this statement—Christ as Mediator—so it is necessary to defend that faith justifies.  For how will Christ be Mediator if we do not use Him as Mediator in justification, if we do not hold that we are counted righteous for His sake?  To believe is to trust in Christ's merits, that for His sake God certainly wishes to be reconciled with us.  Here is a similar point:  Just as we should defend that the promise of Christ is necessary apart from the Law, so also should we defend that faith justifies.  For the Law cannot be performed unless the Holy Spirit is received first.  It is, therefore, necessary to defend that the promise of Christ is necessary.  But this cannot be received except through faith.  Therefore those who deny that faith justifies teach nothing but the Law, both Christ and the Gospel being set aside.
~BOC, Apology, IV (II), 69-70

Virginity is a more excellent gift than marriage, but for Christ's sake each person receives the forgiveness of sins and through faith is regarded righteous before God...

We are justified neither because of virginity nor because of marriage, but freely for Christ's sake, when we believe that for His sake God is merciful to us.  Here perhaps they will cry out that, like Jovinian, marriage is made equal to virginity.  But, because of such racket, we will not reject the truth about the righteousness of faith, which we explained before.  Yet we do not make virginity and marriage equal. For just as one gift excels another, as prophecy surpasses power of speech, the science of military affairs excels agriculture, and power of speech excels architecture, so virginity is a more excellent gift than marriage. Just as a public speaker is no more righteous before God because of his ability to speak than an architect because of his skill in architecture, so a virgin does not merit justification by virginity more than a married person merits it by conjugal duties.  Each person should faithfully serve in his own gift and believe that for Christ's sake he receives the forgiveness of sins and through faith is regarded righteous before God.

Neither does Christ or Paul praise virginity because it justifies, but because it is freer and less distracted with domestic occupations, in praying, teaching, and serving.  For this reason Paul says, "The unmarried man is anxious about the things of the Lord" (I Corinthians 7:32).  Virginity, therefore, is praised because of mediation and study.

~BOC, AP, XXIII (XI), 36-40

We receive justification by faith in Jesus Christ, through the Word of God and as a Work of the Holy Spirit...

Christ, in the last chapter of Luke, commands "that repentance and forgiveness of sins should be proclaimed in His name" (24:27).  The Gospel convicts all people that they are under sin, that they are subject to eternal wrath and death.  It offers, for Christ's sake, forgiveness of sin and justification, which is received through faith.  The preaching of repentance (which accuses us) terrifies consciences with true and grave terrors.  In these matters, hearts ought to receive consolation again.  This happens if they believe Christ's promise, that for His sake we have forgiveness of sins.  This faith, encouraging and consoling in these fears, receives forgiveness of sins, justifies, and gives life.  For this consolation is a new birth and spiritual life.  These things are plain and clear and can be understood by the pious.  They also have testimonies of the Church.  The adversaries cannot say how the Holy Spirit is given.  They imagine that the Sacraments give the Holy Spirit by the outward act (ex opere operato), without a good emotion in the one receiving them, as though, indeed, the gift of the Holy Spirit were a useless manner.

We speak of the kind of faith that is not an idle thought, but that liberates from death and produces a new life in hearts.  This is the work of the Holy Spirit.  This does not coexist with mortal sin.  As long as faith is present, it produces good fruits, as we will explain later.  About the conversion of the wicked, or about the way of regeneration, what can be said that is simpler or clearer?  Let the Scholastics, from so great a host of writers, produce a single commentary upon the Sentences that speaks about the way of regeneration.  When they speak of the habit of love, they imagine that people merit it through works.  They do not teach that it is received through the Word.  They teach just like the Anabaptists teach at this time.  But God cannot be interacted with, God cannot be grasped, except through the Word.  So justification happens through the Word, just as Paul says in Romans 1:16. "[The Gospel] is the power of God for salvation to everyone who believes."  Likewise, he says in 10:17, "Faith comes from hearing."  Proof can be derived even from this:  faith justifies because, if justification happens only through the Word, and the Word is understood only by faith, it follows that faith justifies.
~BOC, AP, IV (II), 61-68

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

The Holy Spirit brings to us the treasures of forgiveness, sonship, and inheritance of eternal life...

We unanimously believe, teach, and confess the following about the righteousness of faith before God, in accordance with the comprehensive summary of our faith and confession presented above.  A poor sinful person is justified before God, that is, absolved and declared free and exempt from all his sins and from the sentence of well-deserved condemnation, and is adopted into sonship and inheritance of eternal life, without any preceding, present, or subsequent works, out of pure grace, because of the sole merit, complete obedience, bitter suffering, death, and resurrection of our Lord Jesus Christ alone. His obedience is credited to us for righteousness.

These treasures are brought to us by the Holy Spirit in the promise of the Holy Gospel.  Faith alone is the only means through which we lay hold on, accept, apply, and take them for ourselves.  This faith is God's gift, by which we truly learn to know Christ, our Redeemer, in the Word of the Gospel and trust in Him.  We trust that for the sake of His obedience alone we have the forgiveness of sins by grace, are regarded as godly and righteousness by God the Father, and are eternally saved.
~BOC, FSD, III, 9-11

The Holy Spirit reveals the treasure of Christ...

Neither you nor I could ever know anything about Christ, or believe in Him, and have Him for our Lord, unless it were offered to us and granted to our hearts by the Holy Spirit through the preaching of the Gospel.  The work of redemption is done and accomplished.  Christ has acquired and gained the treasure for us by His suffering, death, resurrection, and so on.  But if the work remained concealed so that no one knew about it, then it would be useless and lost.  So that this treasure might not stay buried, but be received and enjoyed, God has caused the Word to go forth and be proclaimed.  In the Word He has the Holy Spirit bring this treasure home and make it our own.  Therefore, sanctifying is just bringing us to Christ so we receive this good, which we could not get ourselves.
~BOC, LC, III, 38-39