WASHINGTON, D.C. -- The end of the calendar year provides a good time to take stock of Americans' religion, including the way in which it remains highly intertwined with politics.

Protestants continue to make up the largest religious group in America, totaling 49% of U.S. adults interviewed as part of Gallup's Daily tracking in 2017. Catholics are the next-largest group, at 23% of the population, with Mormons accounting for about 2%. This means that about three-quarters of Americans, overall, identify with a Christian faith.

Another 6% of the population identifies with a non-Christian faith, including Judaism, Islam and others, while 21% of Americans do not have a formal religious identity. All of these groups are within a percentage point of where they were in 2016, suggesting that the shifts seen in previous years have stabilized, particularly the growth among those with no religious identity.

	2016	2017
	%	%
Protestant/Other Christian	48.9	48.5
Catholic	23.0	22.7
Mormon	1.8	1.8
Jewish	2.1	2.1
Muslim	0.8	0.8
Other non-Christian religion	2.5	2.9
No religious identity	20.8	21.3
Gallup

Thirty-seven percent of Americans can be classified as highly religious based on their self-reports of church attendance and the importance of religion in their lives. This is within one percentage point of the 38% recorded last year. Another 30% of Americans are classified as moderately religious and 33% as not religious at all.

	2016	2017
	%	%
Highly religious	38	37
Moderately religious	30	30
Not religious	32	33
GALLUP

Mormons are by far the most religious of the major religious groups in the U.S., with 74% classified as highly religious. Protestants, Muslims and Catholics are more of a mix of highly and moderately religious adults, while Jews and those who identify with another non-Christian religion are the least religious.

	Mormon	Protestant	Muslim	Catholic	Jewish	Other non-Christian religion
	%	%	%	%	%	%
Highly religious	74	50	45	40	19	16
Moderately religious	16	34	37	35	31	36
Not religious	10	16	18	24	50	48
GALLUP, Jan. 2-Dec. 20

The relationship between religiosity and political party identification remained virtually the same in 2017 as in 2016. About half of Republicans are highly religious, compared with about a third of independents and Democrats. Religiosity among the latter two groups is almost identical, including 38% and 39% of independents and Democrats, respectively, who are not religious.

	Republicans		Independents		Democrats
	2016	2017	2016	2017	2016	2017
	%	%	%	%	%	%
Highly religious	51	51	33	32	33	32
Moderately religious	29	29	30	30	30	29
Not religious	20	20	37	38	37	39
GALLUP

Americans who are highly religious are much more likely to approve of President Donald Trump's performance in office than are those who are moderately or not religious. These relationships are not unexpected given the correlation between religiosity and party identification. President Barack Obama had his highest approval ratings in office among those who were not religious, while George W. Bush, like Trump, had his highest approval ratings among the highly religious.

	Highly religious	Moderately religious	Not religious
	%	%	%
Approve of Trump	48	40	28
Disapprove of Trump	46	54	67
GALLUP, Jan. 2-Dec. 20

The relationship between religiosity and Trump job approval is mainly among non-Hispanic white Americans. Trump's approval is 64% among highly religious whites, twice as high as it is among whites who are not religious. There is little relationship between religiosity and views of Trump among nonwhites; approval is below 20% in all three religious groups.

	Non-Hispanic white			Nonwhite
	Highly religious	Moderately religious	Not religious	Highly religious	Moderately religious	Not religious
	%	%	%	%	%	%
Approve	64	54	32	19	18	16
Disapprove	32	42	64	73	74	77
GALLUP, Jan. 2-Dec. 20