The president prayed silently with the congregation during Mass, which was celebrated in the local language The Associated Press reported.
According to the AP, the people were moved by the visit, saying that it symbolizes the reconciliation between the United States and Vietnam and shows that faith is universal.
Bush said later that he and his wife were pleased to spend a "moment to converse with God."
"We were touched by the simplicity and the beauty of the moment. We appreciate very much the congregation for allowing us to come and worship with them," he said.
"A whole society is a society which welcomes basic freedoms and there's no more basic freedom than the freedom to worship as you see fit," Bush said.
“My hope is that people all across the world will be able to express [religious] freedom. And it's our way of expressing our personal faith and, at the same time, urging societies to feel comfortable with, and confident in saying to their people, if you feel like praising God you're allowed to do so in any way you see fit,” he said.
Bush's visit to the church came just days after the United States removed the communist country from its list of the world's worst violators of religious freedom.
Members of Vietnam's six government-approved faiths, including Catholicism, have been packing churches and temples across the country for several years now. While the Communist Party still oversees church administration, many ordinary worshippers say they feel free to express their faith, reports the AP.
The country continues to come under international criticism for harassing members of unapproved Protestant faiths as well as the Unified Buddhist Church of Vietnam, but in its recent report the U.S. government says such harassment has eased in the last year.
.- President George W. Bush joined Vietnamese Protestants and Catholics in prayer on Sunday at the Cua Bac Catholic Church in Hanoi. He also made statements underlining the importance of freedom of worship.