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

Not every thing that belongs in conversion also belongs in the article of justification...

If the article of justification is to remain pure, the greatest attention must be given with special diligence.  Otherwise, what comes before faith, and what follows after it, will be mixed together or inserted into the article of justification as necessary and belonging to it.  For it is not one and the same thing to talk about conversion and to talk about justification.

Not every thing that belongs in conversion also belongs in the article of justification.  Only God's grace, Christ's merit, and faith belong and are necessary to the article of justification.  Faith receives these blessings in the promise of the Gospel, by which Christ's righteousness is credited to us.  From this we receive and have forgiveness of sins, reconciliation with God, sonship, and are made heirs of eternal life.
~BOC, FSD, III, 24-25

Christ connects the promise of the forgiveness of sins to good works...

Christ often connects the promise of the forgiveness of sins to good works, yet not because He means that good works are an atoning sacrifice (for they follow reconciliation).  Christ makes this connection for two reasons.  One is because good fruit must necessarily follow.  He reminds us that if good fruit does not follow, the repentance is hypocritical and fake.  The other reason is that we have need of outward signs of so great a promise.  A conscience full of fear has need of much consolation. Baptism and the Lord's Supper are signs that continually remind, cheer, and encourage despairing minds to believe more firmly that their sins are forgiven.  So the same promise is written and portrayed in good works, in order that these works may remind us to believe more firmly. Those who produce no good works do not encourage themselves to believe, but despise these promises. On the other hand, the godly embrace them and rejoice that they have the signs and testimonies of so great a promise.  So they exercise themselves in these signs and testimonies.  Therefore, just as the Lord's Supper does not justify us by the outward act (ex opere operato) without faith, so alms do not justify us by the outward acts (ex opere operato) without faith.
~BOC, AP, V (III), 155-156

Works can never make a conscience peaceful...

The promise should always be in sight.  Because of His promise.  God wishes to be gracious and to justify for Christ's sake, not because of the Law or our works.  In this promise timid consciences should seek reconciliation and justification.  By this promise they should sustain themselves and be confident that they have a gracious God for Christ's sake, because of His promise. So works can never make a conscience peaceful.  Only the promise can.
~BOC, AP, V (III), 59

By faith alone...

Therefore, it is necessary that faith alone reconciles and justifies. We do not receive forgiveness of sins through other powers of the Law, or because of these: patience, chastity, obedience toward magistrates, and so on. (Nevertheless, these virtues ought to follow faith.) Therefore, we do not receive forgiveness of sins because of love for God, even though this must follow. Besides this way of speaking is well known. At times we use a word for something and use use the same word for the cause and effects of that thing (synecdoche). For example, in Luke 7:47, Christ says, "Her sins, which are many are forgiven--for she loved much." Christ Himself interprets this when He adds, " Your faith has saved you" (7:50). Christ did not mean that the woman had merited forgiveness of sins by that work of love That is why he adds, "Your faith has saved you." But faith is that which freely obtains God's mercy because of God's Word.
~BOC, AP, V (III), 30-32

Christ's suffering, in His human nature, for us...

God's Son truly suffered for us.  However, He did so according to the attributes of the human nature, which He received into the unity of His divine person and made His own.  He did this so that He might be able to suffer and be our High Priest for our reconciliation with God....
~BOC, FE,VII, 14