Commentators explain that Judas's betrayal wasn't a sudden impulse but the result of a hardened heart. Greed, resentment over being rebuked, and disillusionment made him vulnerable. John Calvin notes that when Luke says "Satan entered into him," it signifies a terrifying state where a person, through persistent sin, is completely given over to evil, losing all sense of shame or fear of God. This serves as a solemn warning against nurturing sin in our own hearts.