Faith is a work of the Holy Spirit, by which we are freed from death and terrified minds are encouraged and brought to life...

Truly it is amazing that the adversaries are in no way moved by so many passages of Scripture, which clearly credit justification to faith.  Indeed, Scripture denies this ability to works.  Do they think that the same point is repeated so often for no purpose?  Do they think that these words fell thoughtlessly from the Holy Spirit?  But they have also come up with sophisticated tricks by which they escape these passages.  They say that these passages of Scripture (that speak of faith) ought to be received as referring to faith that has been formed (fides formata).  This means they do not credit justification to faith in any way, but only to love, because they dream that faith can coexist with mortal sin.  Where does this go?  They again abolish the promise and return to the Law.  If faith receives forgiveness of sins because of love, forgiveness of sins will always be uncertain, because we never love as much as we ought to.  Indeed, we do not love unless our hearts are firmly convinced that forgiveness of sins has been granted to us.  So the adversaries, in forgiveness of sins and justification, require confidence in one's love.  In this way, they completely abolish the Gospel about the free forgiveness of sins; although, at the same time, they do not offer this love or understand it, unless they believe that forgiveness of sins is freely received.

We also say that love ought to follow faith, as Paul says in Galatians 5:6: "For in Christ Jesus neither circumcision nor uncircumcision counts for anything, but only faith working through love."

Yet, we must not think that by confidence in this love, or because of this love, we receive forgiveness of sins and reconciliation, just as we do not receive forgiveness of sins because of the works that follow.  But forgiveness of sins is received by faith alone.  Indeed, this is properly called faith because the promise cannot be received except by faith.  Faith, properly called, is what believes this promise.  Scripture speaks of this faith.  Because faith receives forgiveness of sins and reconciles us to God, we are (like Abraham) counted as righteous for Christ's sake before we love and before we do the works of the Law, although love necessarily follows.

Nor, indeed, is this faith an idle knowledge, neither can it coexist with mortal sin.  It is a work of the Holy Spirit, by which we are freed from death and terrified minds are encouraged and brought to life.  Because this faith alone receives forgiveness of sins, makes us acceptable to God, and brings the Holy Spirit, it could be more correctly called "grace making one pleasing to God" (gratia gratum faciens).  It could not be called an effect following faith (i.e., love).
~BOC, AP, IV (II), 107-116