Five solae - Sola Fide ("by Faith Alone")

Sola Fide ("by Faith Alone")

Sola fide is the teaching that justification (interpreted in Protestant theology as "being declared just by God") is received by faith only, without any mixture of or need for good works, though in classical Protestant theology, saving faith is always evidenced, but not determined, by good works. Some Protestants see this doctrine as being summarized with the formula "Faith yields justification and good works" and as contrasted with the Roman Catholic formula "Faith and good works yield justification."

However, this is disputed by the Roman Catholic position as a misrepresentation; they claim it is better contrasted with a comparison of what is meant by the term "justification": both sides agree that the term invokes a communication of Christ's merits to sinners, not a declaration of sinlessness; Luther used the expression simul justus et peccator ("at the same time justified and a sinner"). Roman Catholicism sees justification as a communication of God's life to a human being, cleansing him of sin and transforming him truly into a son of God, so that it is not merely a declaration, but rather the soul is made actually objectively righteous.

The Protestant response to this criticism is to state that this is a misrepresentation of their doctrines. Martin Luther taught that faith is not human response, but the work of God through the means of grace. Faith is the righteousness of God that is accomplished in us through word and sacraments. Law and gospel work to kill the sinful self and to accomplish the new creation within us. This new creation within us is the faith of Christ. If we do not have this faith, then we are ungodly. Indulgences or human prayers add nothing—they are nothing. Everyone has some kind of faith—usually a faith in themselves. But we need God to continually destroy self-righteous faith and to replace it with the life of Christ. We need the faith that comes from God through law and gospel, word and sacraments. In the founding document of the Reformation, the 95 Theses, Luther said that 1.) “When our Lord and Master Jesus Christ said, ‘Repent’ (Matthew 4:17) He willed the entire life of believers to be one of repentance.” and 95.) And thus be confident of entering into heaven through many tribulations rather than through the false security of peace (Acts 14:22).

The true distinction, therefore, between the Protestant and the Catholic view of Justification is not an issue of being "declared righteous" versus being "made righteous", but rather it is the means by which one is Justified. In Catholic theology righteous works are considered meritorious toward salvation in addition to faith, whereas in Protestant theology, righteous works are seen as the result and evidence of a truly Justified and Regenerate believer who has received these by Faith Alone. The actual effectual means by which a person receives Justification is also a fundamental division between Catholic and Protestant belief. In Catholic theology, the means by which Justification is applied to the soul is the Sacrament of Baptism. In Baptism, even of infants, the grace of Justification and Sanctification is "infused" into the soul, making the recipient Justified even before he has exercised his own faith (or indeed in the case of an infant who is baptized, before he even has the ability to consciously understand the Gospel and respond with faith). In Catholic theology, faith is not a prerequisite to Justification. For the Catholic, baptism functions "ex operere operato" or "by the working of the act", and thus is the efficient and sufficient act to bring about Justification. In Protestant theology, however the Faith of the individual is absolutely necessary and is itself the efficient and sufficient response of the individual that effects Justification.

The Sola fide doctrine is sometimes called the material cause or principle of the Reformation because it was the central doctrinal issue for Martin Luther and the other reformers. Luther called it the "doctrine by which the church stands or falls" (Latin, articulus stantis et cadentis ecclesiae).