Sola fide

Sola fide, meaning "faith alone," is a Protestant Christian doctrine that teaches sinners are forgiven and declared “not guilty” through faith—apart from good works or religious deeds. Protestants traditionally believe that this doctrine of salvation is the cornerstone of Christianity, the very teaching "upon which the church stands or falls".

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. Methodism affirms the doctrine of justification by faith alone, 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.

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, Catholicism teaches that salvation is by faith and works, 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." Eastern Orthodoxy shares a similar view, teaching that salvation requires both faith and the sinner’s active cooperation.