My mother has a fairly rare heart condition known as Hypertropic Cardiomyopathy. It is a disease of the muscle of the heart in which a portion of the muscle of the heart is thickened without any obvious cause. It’s a leading cause of sudden cardiac death in any age group and causes disabling symptoms. Apparently with this disease the heart muscle increases in size and causes the heart muscle to thicken. It causes disruptions of the electrical functions of the heart. My mum recently went into the ICU with an irregular heart beat and received shock treatment - electrical impulses to stimulate the heart to beat in time, rather than irregularly.
Pharaoh had some shock treatment to his hardened heart also, in the form of signs and wonders and plagues. God was trying to reveal Himself to Pharaoh. I am no better than Pharaoh, yet when God shocked my spiritual heart it began to function once again as it should. I saw the Cross and was shocked by what God had done for me and the forgiveness that He was offering me and humbled by such an act of love.
When God shocked Pharaoh’s heart it hardened all the more and was headed for certain cardiac arrest.
How does your heart respond to God’s promptings? Are you shocked by your sin and your need to humbly submit to Him and accept His forgiveness? Are you shocked by the Cross of Christ? God says to me as He did to Pharaoh "You will know that I am God!" which means He is in command and I am not.