VATICAN CITY (CNS) -- Prejudices and preconceptions can block people from finding faith, Pope Francis said, even to the point of making them unable to recognize God standing before them.

In the Gospel, the Judeans, who were "scandalized" when Jesus told them he came down from heaven, "are obstructed in their faith by their preconception of his humble origins, and they are obstructed by the presumption therefore that they have nothing to learn from him," the pope said before praying the Angelus in St. Peter's Square Aug. 11.

Reflecting on the day's Gospel reading from St. John, Pope Francis urged Christians to "beware of preconceptions and presumptions," like those of the Judeans who were convinced that the Messiah could not come from among ordinary people.

Preconceived notions "prevent sincere dialogue" and foment "rigid mindsets" that leave no space for uncomfortable or startling ideas, he said.

Despite Jesus' numerous miracles, the pope said, the Judeans failed to recognize him as God "because they carry out their religious practices not so much in order to listen to the Lord, but rather to find in them the confirmation of what they think."

"They are closed to the word of the Lord and look for confirmation of their own thoughts," he said.

Rather than seek an explanation from Jesus, the Judeans murmur among themselves against Jesus "as though to reassure each other of what they are convinced about and they shut themselves in, they are closed up in an impenetrable fortress," Pope Francis said.

As a result, "they are unable to believe," he said. "The closure of the heart -- how much harm it does, how much harm!"

The pope encouraged Christians to take care to listen to God in life and in prayer rather than look to him for "a confirmation of our convictions, our judgments, which are prejudices."

Solely looking to God for confirmation "does not help us to encounter God, to truly encounter him, nor to open ourselves up to the gift of his light and his grace, in order to grow in goodness, to do his will and to overcome failings and difficulties," he said, noting that when people are closed in their way of thinking and praying, "that faith and that prayer are not true."

After praying the Angelus, Pope Francis also recalled the anniversary of the atomic bombings of Hiroshima and Nagasaki which took place Aug. 6 and Aug. 9, 1945, praying for the victims of the bombings and asking for prayers for peace in Ukraine, the Middle East, Sudan and Myanmar.