How do we know all men are sinners?

The teaching that all men are sinners is repeated throughout the Scriptures. Romans 3:23 affirms that 'for all have sinned and fall short of the glory of God'. This doctrine also highlights the universality of human sinfulness; it is echoed in Romans 2:12-16, which indicates that whether or not people have the law, they are still judged as sinners. This underscores the need for salvation, as no one can achieve righteousness through their works. Man's sinful nature is a theme deeply embedded in Reformed theology, demonstrating humanity's need for divine grace and mercy through Christ.