How do we know that regeneration is the work of God alone?

In John 3:3, Jesus clearly states that unless a man is born again, he cannot see the Kingdom of God. This emphatic declaration underscores that regeneration is not achieved by human effort or intellect, but is solely the work of God. It emphasizes the necessity of divine intervention in transforming a heart that is naturally inclined towards sin. This perspective is vital as it places the power of salvation firmly in God's hands, affirming that it is through His mercy and grace that anyone comes to faith, and not through their own abilities or knowledge.