How do we know faith alone is necessary for salvation?

Faith is essential for salvation because it is the means by which we receive the righteousness provided by Christ. Philippians 3:9 highlights that our own righteousness falls short, and it is through faith in Christ that we are credited with God's righteousness. This doctrine, rooted in the Reformation and upheld in the teachings of Scripture, emphasizes that no amount of obedience to the law can justify us before God. As we trust in Christ, we acknowledge that our salvation is entirely dependent on His perfect work rather than our flawed efforts.