The results show that fewer than half of Christian respondents said they think the commander in chief is doing a good job. Catholics were most likely to approve of the president's performance at 44 percent, followed by Protestants at 37 percent and Mormons at 18 percent.
Among non-Christians, 72 percent of Muslims said they approve of the president's performance, followed by Jews at 55 percent and those with no religious affiliation at 54 percent. In a catch-all group of other non-Christians, 59 percent were favorable to the president.
Gallup's numbers are based on tracking polls conducted during the first half of 2014, a time when, on average, 43 percent of U.S. residents approved of Obama.
Since Obama became president in January 2009, Muslims have had the highest opinion of his performance and Mormons the lowest, with other religious groups lining up in the same order. But the share of each group's approval is currently 5 to 7 percentage points below the average for his presidency.
Overall, about half of U.S. residents identify as Protestant and 25 percent as Catholic.
Religious groups also vary widely in their party identification. Gallup suggested that Obama's standing with each group has more to do with his being a Democrat than with the policies he has backed as president.
Gallup's daily tracking polls involved a total of 88,000 interviews. There were 552 Muslims among the respondents and at least 1,700 from every other religious group.