How do we know salvation comes through faith and not works?

The assurance that salvation is not through works is rooted in the observation that no one can fully adhere to the law. Romans 3:20 underscores this by stating that 'by the deeds of the law shall no flesh be justified.' The law reveals sin but cannot provide the means for righteousness. Only through faith in Jesus Christ, whose righteousness is imputed to believers, can one attain salvation. This is further illustrated in Romans 10:9-10, which articulates the necessity of confessing with the mouth and believing with the heart, showcasing that belief is foundational to salvation, not legalistic observance.