How do we know the doctrine of salvation by grace through faith is true?

The doctrine of salvation by grace through faith is grounded in biblical teaching, particularly in passages such as Ephesians 2:8-9, which states that salvation is a gift from God, not a result of works. The cross of Christ serves as the ultimate demonstration of this grace, wherein God, through Christ's sacrifice, reconciles sinners to Himself. The theological implications of the cross highlight that our faith must rest in His finished work alone, affirming the truth of salvation by grace as central to the gospel.