How do we know that salvation is all of God?

The sovereignty of God is a central theme in Reformed theology, emphasizing that salvation is a work solely conducted by God. Romans 9 explains that God has mercy on whom He will have mercy and hardens whom He wills, demonstrating His absolute authority over salvation. This means that individual salvation cannot be based on human effort or merit but is solely an act of God's grace. The notion that we contribute to our justification diminishes the glory of God and the power of grace, as it contradicts the biblical teaching that our standing before God rests entirely on the finished work of Christ. Therefore, believers can be assured that their salvation is secure because it depends not on their actions but on God's immutable purpose.