, meaning "by faith alone," is a Protestant Christian doctrine that teaches sinners are justified Keller, Brian R., Believe it or not: You are forgiven through Christ! , p7, "The Greek verb for 'justified' means that a judge declares people 'not guilty' of all charges. They are in a constant state of being declared not guilty, 'freely by his grace. Strong's Greek: 1344. δικαιόω Penninton, R., The Answer to All Your Questions about the book of Revelation, p117, "Justified - 'Declared not guilty' This means that we are considered not guilty in God's sight even through our sins were great." Bauer, W., Danker, F. W., Arndt, W. F., & Gingrich, F. W., A Greek–English Lexicon of the New Testament and Other Early Christian Literature, Chicago: University of Chicago Press, p220, "to render a favorable verdict, vindicate. (as activity of humans: justify, vindicate, treat as just)" WELS Topical Q&A: Witnessing to Roman Catholics, "God declares us 'not guilty' on the basis of Jesus' perfect sacrifice on the cross (justification), and that verdict becomes our personal possession through faith in Jesus (justification by faith, not by works)." through JustifyingRt Revd Forbes, William MOST Protestants reckon four kinds of faith (of that faith, I mean, by which we believe, not of that which is believed), viz.: historical, wonder-working, temporary, and justifying faith . Le Blanc, Louis IV. This is the faith which is called historical by our people. .... Our schools call this temporary faith: the name taken from the words of Christ which we just cited. ... This is the faith by which miracles are performed, whence it has also taken its name. ... IX. Finally, there is another faith to which Scripture attributes our righteousness and salvation, to which it vehemently and frequently exhorts us, and which it adorns with the highest praises and commendations. And this is what we call justifying, salvific, living, and true faith. faith—apart from good works or religious deeds.Epistles of Paul: Romans 4:4, "Now to a person who works, his pay is not counted as a gift but as something owed. But to the person who does not work but believes in the God who justifies the ungodly, his faith is credited to him as righteousness." Romans 11:6, "Now if it is by grace, then it is not the result of works—otherwise grace would no longer be grace." Ephesians 2:8-9, "Indeed, it is by grace you have been saved, through faith — and this is not from yourselves (touto ouk ex hymōn), it is the gift of God — not by works (ouk ex ergōn), so that no one can boast." Galatians 3:3, "How foolish can you be? After starting your new lives in the Spirit, why are you now trying to become perfect by your own human effort (sarki epiteleisthe)?" Galatians 2:16, "We know that a person is not justified by the works of the law but through faith in Jesus Christ. So we also believed in Christ Jesus that we might be justified by faith in Christ and not by the works of the law, because no one will be justified by the works of the law." Titus 3:5, "he saved us, not because of righteous things we had done, but because of his mercy." 2 Timothy 1:8-9, "join with me in suffering for the gospel, by the power of God, who has saved us and called us to a holy life — not because of anything we have done but because of his own purpose and grace." Protestants traditionally believe that this doctrine of salvation is the cornerstone of Christianity, the very teaching "upon which the church stands or falls".Olson, M.K., John Wesley's Doctrine of Justification, p9

In classical Protestant theologies, works are the natural evidence of faith, but they do not determine salvation. Confessional Lutheranism sees justification as free forgiveness, received only through faith. Without faith, God's forgiveness is rejected and its benefits are forfeited.Ecumenical Discussions on Justification – the Joint Declaration on the Doctrine of Justification, Lutheran Church – Missouri Synod, 2018, p5Keller, Brian R., Believe it or not: You are forgiven through Christ!, p2 Methodism affirms the doctrine of justification by faith alone,Article IX, The Articles of Religion of the Methodist Church, The United Methodist Church, "Wherefore, that we are justified by faith, only, is a most wholesome doctrine, and very full of comfort." but holds that holy living with the goal of Christian perfection (entire sanctification) is essential for salvation; maintenance of sanctification is contingent on continual faith in and obedience to God. In contrast to classical Protestant theology, Free Grace theology sees justification as being received through a single act of faith that guarantees eternal security independent of personal perseverance, though they may experience temporal discipline from God. In this view, good works are not necessary proofs of salvation but rather the ground of our degree of eternal reward.

Anabaptist theology categorically rejects the Lutheran and Reformed doctrine of sola fide, and instead emphasizes a "faith that works"; Anabaptists teach that "justification [began] a dynamic process by which the believer partook of the nature of Christ and was so enabled to live increasingly like Jesus."

Unlike the Protestant teaching of faith apart from works,WELS Topical Q&A: Inaccurate teachings on Catholic salvation theology, "Why do we think the Catholic teaching 'by faith and works' is not correct? Because the Bible says we are saved by faith not by works. We encourage you to read Roman 3, Ephesians 2, and Galatians 3. Paul says that adding just one work to faith destroys both grace and faith (read Galatians 5). How can both Catholics and Lutherans say we are saved by grace when they teach so differently about faith? It is because they are using different definitions of saving grace. For Catholics saving grace is an ability God puts into us that enables us to do the works that will enable us to complete our salvation. For Lutherans (and, we believe, the Bible) saving grace is an attitude of God toward us by which he forgives our sins only for Christ's sake, not in any way because of anything we do. In other words for Catholics saving grace is in us. For Lutherans it is in Christ alone. Though the Catholic church denies that it teaches that salvation is by works alone, it is correct to say that the Catholic church teaches salvation by works. This is because if you mix faith and works as the cause of salvation, this equals salvation by works (see Romans 11:6)." Catholicism teaches that salvation is by faith and works,Sungenis, Robert A., Not By Faith Alone, Queenship Publishing Company, 1997, Nihil Obstat and Imprimatur granted: p81, "both faith and works are necessary for justification" p136, "Faith and works, though separate entities, must be joined together for salvation to occur." p571, "Catholicism...holds that faith and works are required for justification" p591, "Only when we understand that God views our faith and works within the realm of grace — a grace that seeks to please God personally not judicially — can there be any gratuity given to man or righteousness deemed to him. This is the Catholic view." holding to the concept of fides formata — faith formed by charity. Catholic theology emphasizes that faith must be accompanied by personal "merit" and the "observance of the commandments."Catechism of the Catholic Church (1992): Paragraph 1814 "Faith is the theological virtue by which we believe in God and believe all that he has said and revealed to us, and that Holy Church proposes for our belief, because he is truth itself. By faith "man freely commits his entire self to God." For this reason the believer seeks to know and do God's will. "The righteous shall live by faith." Living faith "work(s) through charity." Paragraph 1815: "The gift of faith remains in one who has not sinned against it. But "faith apart from works is dead": when it is deprived of hope and love, faith does not fully unite the believer to Christ and does not make him a living member of his Body." Paragraph 2010: "Since the initiative belongs to God in the order of grace, no one can merit the initial grace of forgiveness and justification, at the beginning of conversion. Moved by the Holy Spirit and by charity, we can then merit for ourselves and for others the graces needed for our sanctification, for the increase of grace and charity, and for the attainment of eternal life." Paragraph 2036: "The authority of the Magisterium extends also to the specific precepts of the natural law, because their observance, demanded by the Creator, is necessary for salvation." Paragraph 2068: "The Council of Trent teaches that the Ten Commandments are obligatory for Christians and that the justified man is still bound to keep them; The Second Vatican Council confirms: "The bishops, successors of the apostles, receive from the Lord . . . the mission of teaching all peoples, and of preaching the Gospel to every creature, so that all men may attain salvation through faith, Baptism and the observance of the Commandments Paragraph 2027: "we can merit for ourselves and for others all the graces needed to attain eternal life, as well as necessary temporal goods." Paragraph 847: "Those who, through no fault of their own, do not know the Gospel of Christ or his Church, but who nevertheless seek God with a sincere heart, and, moved by grace, try in their actions to do his will as they know it through the dictates of their conscience - those too may achieve eternal salvation." Eastern Orthodoxy shares a similar view, teaching that salvation requires both faith and the sinner's active cooperation.Stavropoulos, Christophoros, Partakers of the Divine Nature, in Eastern Orthodox Theology: A Contemporary Reader, p188, "The work of our theosis, our union with God, is not transmitted to us in some mechanical fashion. Our weakened human nature will not be transformed magically. The change will happen in conjunction with our own efforts. It will be realized with the cooperation of man and God. This subjective aspect of our union provides the way of theosis which we must follow."

Origin of the term

Although modern Catholic scholars are against Luther's use of the word "only", Catholic sources before the Reformation had done the same.Fitzmyer, Joseph A., Romans, A New Translation with Introduction and Commentary, pp360-362, "Although alleyn/alleine finds no corresponding adverb in the Greek text, two of the points that Luther made in his defense of the added adverb were that it was demanded by the context and that sola was used in the theological tradition before him." In 1916, Lutheran scholar Theodore Engelder published an article titled "The Three Principles of the Reformation: Sola Scriptura, Sola Gratia, Sola Fides ("only scripture, only grace, only faith").

Martin Luther Martin Luther elevated sola fide to the principal cause of the Protestant Reformation, the rallying cry of the Lutheran cause, and the chief distinction of the Lutheran and Reformed branches of Christianity from Roman Catholicism.

Luther added the word allein ("alone" in German) to Romans controversially so that it read: "So now we hold, that man is justified without the help of the works of the law, alone through faith".. The word "alone" does not appear in the Greek manuscripts. and Luther acknowledged this fact, but he defended his translation by maintaining that the adverb "alone" was required by idiomatic German:Martin Luther, On Translating: An Open Letter (1530), Luther's Works, 55 vols. (St. Louis and Philadelphia: Concordia Publishing House and Fortress Press), 35:187–189, 195; cf. also Heinz Bluhm, Martin Luther Creative Translator (St. Louis: Concordia Publishing House, 1965), pp. 125–137.

Luther further claimed that sola was used in theological traditions before him and this adverb makes Paul's intended meaning clearer:

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