How do we know salvation is by grace through faith?

The doctrine of salvation by grace through faith is rooted in the belief that it is solely the work of Christ that saves, not any actions or decisions we might undertake. As mentioned in Ephesians 2:8-9, it is by grace we have been saved through faith, and this not from ourselves; it is a gift of God, not by works, so that no one can boast. This principle emphasizes that our confidence in salvation rests in the sufficiency of Christ's sacrifice, which is the foundation for our hope and assurance, demonstrating how salvation is entirely a gift of God's grace.