How do we know grace is the only means for salvation?

The Bible clearly teaches that grace is the unearned favor of God extended to us through Jesus Christ. Ephesians 2:8-9 states that we are saved by grace through faith and not by works, so that no one can boast. Similarly, Romans 10:4 declares that Christ is the end of the law for righteousness for everyone who believes, underscoring that faith in Christ alone opens the way to salvation. The ministry of the Spirit gives life, contrasting with the death brought by the law, further affirming grace as the means of salvation.