“If we keep in mind how variegated medieval catholicism was, the legitimacy of the reformers' claim to catholicity becomes clear.
"Substantiation for this understanding of the gospel came principally from the Scriptures, but whenever they could, the reformers also quoted the fathers of the catholic church. There was more to quote than their Roman opponents found comfortable"
“In the end, the Council of Trent ended up (in true Roman fashion) condemning the true heritage, and canonizing its own path. In its decrees, Trent "selected and elevated to official status the notion of justification by faith plus works, which was only one of the doctrines of justification [found] in the medieval theologians and ancient fathers. When the reformers attacked this notion in the name of the doctrine of justification by faith alone -- a doctrine also attested to by some medieval theologians and ancient fathers-- Rome reacted by canonizing one trend [the wrong one] in preference to all the others. What had previously been permitted (justification by faith and works), now became required. What had been previously been permitted also (justification by faith alone), now became forbidden. In condemning the Protestant Reformation, the Council of Trent condemned [the better part of] its own catholic tradition" (Pelikan 46-49, 51-52).
— Jaroslav Pelikan (Lutheran, scholar of Christianity history, theology and medieval intellectual history, later Orthodox convert), The Riddle of Roman Catholicism (New York: Abingdon Press, 1959, More: http://beggarsallreformation.blogspot.com/2010/09/trajectory-of-church-history.html
The Roman Catholic reaction to Luther and to sola fide in higher levels today can seem overall quite moderate, and often nuanced in allowing justification by faith, but not by a faith apart from works.
The Joint Declaration on the Doctrine of Justification states in part,
31.We confess together that persons are justified by faith in the gospel "apart from works prescribed by the law" (Rom 3:28). Christ has fulfilled the law and by his death and resurrection has overcome it as a way to salvation. We also confess that God's commandments retain their validity for the justified and that Christ has by his teaching and example expressed God's will which is a standard for the conduct of the justified also.
37.We confess together that good works - a Christian life lived in faith, hope and love - follow justification and are its fruits. When the justified live in Christ and act in the grace they receive, they bring forth, in biblical terms, good fruit. http://www.vatican.va/roman_curia/pontifical_councils/chrstuni/documents/rc_pc_chrstuni_doc_31101999_cath-luth-joint-declaration_en.html
On 29 October (2008), two days before Reformation Day, Benedict spoke on the "theology of the cross" in his General Audience address, and states,
And to the Christians of Rome he reasserts that "all have sinned and fall short of the glory of God, they are now justified by his grace as a gift, through the redemption which is in Christ Jesus" (Rm 3: 23-24). And he adds "we hold that a man is justified by faith apart from works of the law" (ibid., v. 28). At this point Luther translated: "justified by faith alone"...
Being just simply means being with Christ and in Christ. And this suffices. Further observances are no longer necessary. For this reason Luther's phrase: "faith alone" is true, if it is not opposed to faith in charity, in love. Faith is looking at Christ, entrusting oneself to Christ, being united to Christ, conformed to Christ, to his life. And the form, the life of Christ, is love; hence to believe is to conform to Christ and to enter into his love. So it is that in the Letter to the Galatians in which he primarily developed his teaching on justification St Paul speaks of faith that works through love (cf. Gal 5: 14)." (Pope Benedict XVI,11/19/08 General Audience; http://www.vatican.va/holy_father/benedict_xvi/audiences/2008/documents/hf_ben-xvi_aud_20081119_en.html)
Benedict is still teaching works justify as one unit with faith, but the fact is that “faith alone” is not opposed to faith in charity, in love, but the sola refers to faith being what actually appropriates justification, but not a type of faith that will not effect confession of the Lord Jesus in word in deed, baptism normally being the first outward formal expression of that, and which confession "justifies" that the person has saving faith. For as faith is known by its fruits, so man is judged by His words and works, manifesting whether he had true faith — though some are saved with works failing the test — (1Cor. 3:15) and is “worthy” of rewards given in grace, (Mt. 25:33-40; Heb. 10:35; Rv. 3:4) — though what all truly deserve is damnation — (Rm. 6:23) or was a false believer, professing by not possessing true faith.
Thus Paul can say that "But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness," (Romans 4:5) as well as (regarding judgment) "For not the hearers of the law are just before God, but the doers of the law shall be justified. " (Romans 2:13)
Note that the “further observances are no longer necessary” quote above, taken form a long discourse, is referring to the ceremonial law, as well as Pharisaical interpretations and requirements according to Benedict, though the latter is not what Paul is referring to in speaking of the Law, nor is the exclusion of works restricted to that system, (Titus 3:5) but any works of righteousness by which man earns eternal life, or rests upon them for acceptance with God as one worthy, rather than casting all His faith upon the risen Lord Jesus to save Him by His sinless shed blood, and therefore he follows Him, which confession “justifies”his faith as salvific. (Rm. 10:9,10)