How does God harden a heart?

In the context of Pharaoh, Scripture reveals that God hardened his heart to demonstrate His power (Exodus 7:3). The hardening of the heart occurs not through direct action but often by God's passive allowance, as He lifts His grace and lets individuals follow their sinful inclinations. When God leaves a person alone, they can become increasingly hardened in their rebellion against Him, as echoed in Romans 1:24, where God gives individuals over to their own sinful desires. This process underscores humanity's natural state of enmity with God and highlights the need for divine intervention through grace.