How do we know the law is written in our hearts?

Romans 2:16 indicates that God's law is written on the hearts of all people, suggesting that regardless of one’s background or knowledge of Scripture, there exists an inherent understanding of God's moral requirements. This law serves as a witness against our actions and thoughts, ensuring accountability before God. It establishes a universal moral compass that reflects God's character, showing that humanity is aware of moral goodness and evil, even without verbal revelation of the law.