How do we know that salvation is by God's mercy?

According to Ephesians 2:4-5, the essence of our salvation lies in God's rich mercy. This affirms that it is not by our own righteousness or efforts that we attain salvation, but through God's compassionate intervention. When Paul states, 'But God, who is rich in mercy,' he emphasizes that amid our spiritually dead state, God takes the initiative to grant us life through Christ. This underscores the doctrine of total depravity, which asserts that we are unable to save ourselves due to our sinful nature. God's mercy, then, acts as the bridge that reconciles us to Himself, providing us with the hope of eternal life through Christ. In His infinite compassion, God bestows upon us grace that we do not deserve, highlighting the critical role His mercy plays in redemption.