How do we know that God changes our heart?

The evidence of a changed heart manifests in new desires, affections, and a hatred for sin. As stated in 2 Corinthians 5:17, anyone who is in Christ is a new creation; old things pass away, and all things become new. The believer's attitude toward sin shifts from indifference to genuine sorrow and loathing of their former ways. This work is not something we achieve through our own efforts but is a result of God's grace and sovereignty in our lives, affirming the new birth He has provided.