It occurs to me that the biggest problem I have with the Catholic Church (and with the New Perspective on Paul for that matter) is the confusion of the doctrine of justification by faith alone and the doctrine of sanctification. Although the two are very closely related, they are not to be fused together into one doctrine. To do so undermines the 'sola' of 'sola fide'.
Justification And Sanctification Simply Explained
In order to understand Justification and Sanctification, one must see their place in the 'Order of Salvation', commonly referred to as the 'Ordo Salutis'. The Order of Salvation as I understand it, as well as most of church history, is as follows.
These can be divided up into four categories,
1. Set Apart For Salvation-Election and Gospel.
2. Already Saved-Regeneration, Conversion, Justification, and Adoption.
3. Being Saved-Sanctification and Perseverance.
4. Future Salvation-Glorification.
In Election God chose those who would believe to salvation, not based on their belief or any goodness in them, but solely for His good pleasure. The Gospel is preached to them by the power of the Holy Spirit and the Holy Spirit, through the Gospel call, sets them apart for salvation.
In Regeneration the Holy Spirit wakes the dead, and imparts faith and repentance (Conversion). Upon Conversion they are declared righteous by God Himself (Justification) and as such they receive Adoption as children. All this is God's work for and in us.
In Sanctification we become co-workers with God as He makes us more holy (like Christ), and we strive for the same holiness. Perseverance is also done in cooperation with God as we are kept by God and continue in faith and repentance.
Glorification is the goal of the 'Order of Salvation' in general. Glorification occurs not at death, but at the resurrection, which takes place at the return of Christ.
Having now set the context for salvation, we will turn our attention to proper definitions of Justification and Sanctification.
Justification is the act of God occurring after conversion (faith and repentance) by which God forgives us for all sin that we have committed and declares us righteous on the basis of faith in Christ.
Sanctification is an act of God and man together by which man is conformed to the image of Christ. Not only are God and the individual Christian at work in sanctification, but also the community of believers at large are working for the common sanctification of one another.
Justification and Sanctification are similar in the respect of our standing before God.
Justification says that we are righteous and Sanctification makes us what Justification says we are. But even in this similarity there is much that contrasts the two doctrines. Justification is a legal term which states that in the eyes of the court we are not just innocent, but righteous. Sanctification is a practical term that takes into account the fallenness of each and every one of us and prepares us for the day when we must appear before the Judge of all creation. But we have this confidence, that Sanctification will be completed when we receive our new bodies.
It must be said that Sanctification does not save anyone. Sanctification is a response of our new nature to the fact of Justification. It is fed by the justified one's desire to be what God has declared him to be.
So don't confuse Justification with Sanctification. Do not depend on your Sanctification for your salvation. This is a very grievous error that will cost you your soul. Those who depend on their own works are not depending on Christ. Those who depend on their own works will never find rest. Rest is found only through faith in Christ, which results in the Judge of Heaven making the declaration, 'Justified, now be Just'.
Recommended Reading: John 3:1-21, Romans, Galatians, Ephesians 1-2, James 2:14-26