[2] A range of views on various world religions is explored as Bill Maher travels to numerous religious destinations including Jerusalem, the Vatican, and Salt Lake City, interviewing believers from a variety of backgrounds and groups.

[11] Creationist Ken Ham of the group Answers in Genesis, who appeared in the film,[12] was critical of what he called Maher's "deception" to obtain the interview.

Its per-screen receipts were almost three times those of a competing film to which it has been compared in the media, the politically conservative An American Carol,[18][19][20][21] which edged out Religulous to finish at #9 over the same weekend, but had a per theater average of only $2,325.

The site's critical consensus reads, "Religulous is funny and offensive in equal measure, and aims less to change hearts and minds than to inspire conversation.

"[36] The documentary received some negative reviews, with Rick McGinnis of Metro concluding that, "Maher is preaching to the choir with an undisguised dishonesty that only the true believers will forgive.

"[37] James Berardinelli wrote, "If the subject of religion is as important to Maher as he claims during his end comments, then he should have followed those words with actions and made a movie that's more than a sum of inauthentic interviews, ranting attacks, and obvious observations.

"[39] In a review for The New York Times, Stephen Holden notes that when Maher "turns from evangelical Christianity to Judaism and Islam, its tone becomes uncertain and its rhythm choppy".

"[42] Claudia Puig of USA Today wrote: "those with a taste for irreverent humor and clear-eyed analysis will find it funny, enlightening and disturbing.

"[43] Kirk Honeycutt of The Hollywood Reporter characterized the film as "An often hilarious but relentlessly shallow attack on religious fundamentalism by humorist Bill Maher".

"[45] Scott Indrisek wrote at Style.com that: "Religulous earns many of its laughs from skillful editing, with Maher's interviews jazzed up by video clips".