Christ spread the Sacred Heart devotion through a French nun, St. Margaret Mary Alacoque, to counter the heretical teaching that man was incapable of loving a severe God, a teaching promoted by a French bishop named Cornelius Jansen.
Father John Hardon, S.J. explains that Jansenism, named after its 17th-century originator, Bp. Jansen, taught that God did not die for those men He had arbitrarily chosen to be damned. No matter what these men did they would not attain salvation, according to Jansen. In addition, Jansen taught, that God was severe to those He would save. As noted by Fr. Hardon:
Jansenism gave expression to this caricature of the divinity by requiring extraordinary penance of the faithful to placate this God of anger; only after such penance was performed and the soul became purified of all self love should anyone dare approach the Holy of Holies in the Sacrament of the Eucharist.
Putting his finger on the core issue, Fr. Hardon explains, "But there is one basic link in this chain of errors. It is the false belief that we do not have a free will with which we can lovingly respond to God's mysterious and unfailing love for us." Today the problem certainly isn't Jansen's rigoristic approach to man's inability to appease God. It is, says Fr. Hardon a laxist view that pretends God doesn't require men to live according to His commandments owing to the false perception that such obedience is virtually impossible even with grace and free will.
Referencing the teachings of Pope Pius XII, Fr. Hardon clarifies, "Our problem today, so states the Pope, is the danger of underestimating the importance of personal effort in order to profit more than just minimally from the Sacrifice and Sacrament of Christ's love." To overcome both the rigorism of the past and laxity of the present, the Sacred Heart devotion calls Catholics and all men to return the love that God extends to them through Christ's Sacred Heart.
Watch the panel discuss God's mercy in The Download—Sacred Heart.