Solo Christo, or solus Christus, is one of the five solas (or solae) that have come to summarize the key issues of the Protestant Reformation. Solo Christo means “Christ alone” in Latin. The other four solas are sola scriptura (“Scripture alone”), sola fide (“faith alone”), sola gratia (“grace alone”), and sola Deo gloria (“for the glory of God alone”). Each one of these doctrines is vitally important. To dispatch with any one of them will lead to error and a false gospel that is powerless to save.
When the Reformers insisted on solo Christo, they affirmed that we are saved by Christ alone, apart from the merit of any other person. Jesus alone is the King of kings (Revelation 19:16). He alone is our High Priest (Hebrews 4:14). He alone is our Redeemer (Galatians 3:13) and the sole Mediator between God and man (1 Timothy 2:5). The attempt to usurp or share in those positions is a blasphemous arrogation. Assigning those roles to someone else (such as Mary) is equally improper. It is Christ and Christ alone who saves.
It is not our righteousness that saves us; it is Christ’s alone. “He saved us, not because of righteous things we had done, but because of his mercy” (Titus 3:5). “This righteousness is given through faith in Jesus Christ to all who believe” (Romans 3:22). Whatever good works we do and however faithful we are, in the final analysis “we are unworthy servants” (Luke 17:10). Christ and Christ alone is the Worthy One (Revelation 5:9). Solo Christo.
From beginning to end, the gospel uplifts Christ and Christ alone. He is the One who came from heaven to seek the lost (Luke 19:10). He is the One who obeyed the Law perfectly. He is the One who was crucified, and He is the One who rose again. We are the grateful recipients of His bounty. We are the beggars, and He is the Benefactor. We are the lepers, and He is the Healer. We are turmoil, and He is Peace. Solo Christo.
The gospel is not a message of what we must do for God; the gospel is the good news of what God has done for us. Salvation is not essentially about us; it is about Jesus. Solo Christo. In all things, Christ must have the supremacy (Colossians 1:18), and the Reformers restored that biblical doctrine to the church. As Luther wrote, “I must listen to the Gospel. It tells me, not what I must do, but what Jesus Christ, the Son of God, has done for me” (Martin Luther, Commentary on Galatians, Chapter 2, Verses 4–5).