How do we know the doctrine of Christ alone is true?

The doctrine of Christ alone is rooted in biblical truth, notably Paul’s message in Galatians 1:6-8, where he expresses amazement that some are turning away from the true gospel to another. He emphasizes that true salvation is not based on human effort but on God’s grace and the work of Christ alone. Furthermore, Ephesians 2:8-9 clarifies that we are saved by grace through faith—not of works. This teaches us that any gospel which adds human merit contradicts the foundational truth of the Christian faith.