VATICAN CITY (CNS) — Just as you protect your home from thieves, you need to protect your heart from the temptations of the devil, Pope Francis said in a morning homily.

Preaching Oct. 10 during Mass in his residence, the Domus Sanctae Marthae, the pope said Christians should not be shocked that the devil continues to assail them; even after Jesus defeated Satan in the desert, the devil continued to try to tempt him, including when he was dying on the cross.

Christians need to guard and protect their hearts, “just as you protect your home — with a lock,” the pope said, according to Vatican Radio.

“How often do bad thoughts, bad intentions, jealousy, envy enter?” he asked. “Who opened the door? How did those things get in?”

If one does not safeguard his or her heart, the pope said, it becomes a public “square where everything comes and goes, a heart without intimacy, a heart where the Lord cannot speak or even listen.”

The best way to guard one’s heart, he said, is with the daily practice of what is classically called an “examination of conscience.” It does not have to be formal or follow preset questions. It requires only that one is alone, quiet and asks, “What happened in my heart today? What passed through my heart?”

Such a daily practice, the pope said, is the only way to learn to be watchful and to safeguard one’s heart against the “these demons, who are very sneaky and end up tricking all of us.”