Prayer is meant to be "our daily bread, our powerful weapon and the staff for our journey," he said May 25 during his weekly general audience in St. Peter's Square.
In his catechesis, the Pope talked about the Gospel parable of the persistent widow, who incessantly appealed to a corrupt judge for justice.
Judges at the time were supposed to be filled with the fear of God as they impartially and faithfully upheld the laws of Moses, the Pope said. But the judge in this parable was dishonest and only cared about himself. He had no interest in protecting the rights of the weakest and easily exploited members of society, which included widows, orphans and foreigners, he said.
"Faced with the judge's indifference, the widow resorted to her only weapon – to keep incessantly pestering him, presenting him with her appeal for justice," the Pope said.
The judge finally gives in, he said, "not because he is moved by mercy or because his conscience forces him to," but because of her perseverance. He realizes he will never rid himself of her until he delivers a just decision, and so he does, the Pope said.
He said Jesus uses this parable to show that if a widow with no clout or influence could sway an uncaring judge merely through her patient and persistent pleas, then imagine how powerful that same force of prayer is when directed toward a loving, merciful and benevolent God.
Jesus is showing how important and necessary it is to pray tirelessly, all the time and not just every now and then, "when I feel like it," the Pope said.
"We all experience moments of exhaustion and discouragement, above all when our prayers don't seem to work," he said.
Contrary to the stubborn judge, he said, God speedily secures "the rights of his chosen ones who call out to him day and night," according to the Gospel of St. Luke (18:1-8).
But that doesn't mean God will respond when "and in the ways that we want. Prayer is not a magic wand," the Pope said.
When Jesus prayed that his father spare him from "the bitter cup of his passion," he also put himself fully in God's hands, asking that the father's will -- not his own -- be done.
Jesus shows how prayer is about strengthening one's relationship with the father -- transforming one's own wishes and conforming them to God's will, he said.
Prayer "helps us keep our faith in God and to trust him even when we do not understand his will.”
"Prayer is what keeps the faith; without it, faith wavers," Pope Francis said. And it is in prayer that people experience the compassion of God who comes to his children "filled with merciful love."