A new Gallup poll saw 43 per cent make the claim. That's up seven per cent from last year and is the highest level ever for that question.
The number rises to two thirds when only 18 to 49 years olds are quizzed.
For those who claim that "religion is very important" to them, 22 percent said pornography is morally acceptable
KingdomWorks Studios, which has produced a series of sexual purity, labelled the results a "wake up for the church".
Dr Richard D Land, president of Southern Evangelical Seminary, is calling on faith groups to take the issue seriously.
He said: "Every church, temple, mosque, and synagogue in America should consciously seek to be part of a pornography-free counter culture which attempts to inoculate its membership in age-applicable ways against pornography's seductive blandishments.
"With 68% of men in the church viewing porn on a regular basis, it is hard for the church to take the moral high ground. Healing must start from within."
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