How do we know that everyone is under sin?

In Romans 3:9, Paul asserts that both Jews and Gentiles are under sin, demonstrating that sin is a universal condition. Regardless of one’s heritage or understanding, all are guilty and in need of redemption. This truth is foundational in sovereign grace theology, affirming that no one can justify themselves before God based on their merits. Acknowledging that we are all under sin highlights our desperate need for the grace and mercy available in Christ, further illustrating the necessity of His work on the cross for our salvation.