"Solus Christus" is a Latin phrase meaning "Christ alone" or "through Christ alone." It is one of the five solae, key principles of the Protestant Reformation.
 
The doctrine of Solus Christus emphasizes that salvation is achieved solely through the work of Jesus Christ—His life, death, and resurrection—without reliance on human works, merits, or other intermediaries such as saints or clergy. It asserts that:
Christ is the sole mediator between God and humanity, as stated in 1 Timothy 2:5:
"For there is one God and one mediator between God and men, the man Christ Jesus."
His sacrificial death is sufficient for the forgiveness of sins, and no additional human effort or institution can contribute to salvation.
 
This principle stands in contrast to practices in the medieval church that Protestants believed undermined the sufficiency of Christ’s work, such as reliance on indulgences, penance, or the intercession of saints. Solus Christus reinforces the focus on Christ as the exclusive source of grace, hope, and redemption.