Perry White is a Baptist. Perry White has always been portrayed a Protestant Christian, but because of the religion taboo present in the comic book industry during the time the character was created and during subsequent decades, Perry White's religious affiliation has rarely been overtly referred to within published comics. Also, Perry White's position as editor-in-chief at the Daily Planet, a mainstream newspaper with a national reputation, did not lend itself to frequent or overt discussion of his specific religious and denominational affiliation. White has always strived to make The Daily Planet the voice of all the people, without favoring any particular group.
From: "The Toughest Newsboy in Town!", originally printed in Action Comics #461 (July 1976); written by Bob Rozakis, pencilled by Curt Swan, inked by Tex Blaisdell, edited by Julius Schwartz; reprinted in Superman: The Daily Planet (DC Comics: New York, 2006), page 126:
Perry White has strong ethics and values, but he does not wear his religion on his sleeve. There are a number of stereotypes typically applied to fictional Baptist characters. Baptists in fiction are often used as a sort of shorthand for narrow-mindedness, provincialism, intolerance or hypocrisy. These stereotypes do not apply to Perry White, who is one of the most respected civilians in the DC Universe.
White has never been accused of favoritism toward his own denomination or toward conservative Protestant Christians generally. It is probably inaccurate to classify White as a "conservative Christian." He may be liberal, moderate or nominal in his religious observation and personal theological views. But if he were truly a conservative Protestant or an Evangelical there would have been some hint of such disposition after appearing in over six decades of comic book stories. We know from the comics that White and his family at least observe Christmas and Easter. Exactly what type of Baptist this character is (whether he is quietly a regular churchgoer and fervent believer, or whether he is only a nominal Baptist who merely retains this denominational affiliation from his childhood, or something in between) we do not know for sure. Such details might be open to interpretation, or might differ among writers in how they think about the character's unprinted back-story.
From: Bruce Bachand, "Interview: Elliot S! Maggin", published in Fanzing (The Independent Online DC Comics Fan Magazine) Issue #9, August 1998 (http://www.fanzing.com/mag/fanzing09/iview.shtml; viewed 6 December 2005):
Elliot S! Maggin was the principal scriptwriter for DC Comics' Superman titles during the 1970's up until the mid-1980's. He has written two Superman novels (Last Son Of Krypton and Miracle Monday, both which are currently out of print) as well as numerous other stories, articles, interviews and projects. One of his most recent publications is the novel KINGDOM COME (which is available through Warner Books) which came out in February 1998. It is based on the very successful DC comic book mini-series KINGDOM COME by Mark Waid and Alex Ross. (It is well worth mentioning that Ross contributes a number of new painted illustrations to the Maggin novel!). Sales have been steady for the Maggin novelization. It is over one hundred thousand words full of action, characterization, and plot sculpting.
BRUCE BACHAND [interviewer]: Do you see Superman as a man who prays and/or worships God regularly? If so, what would the Man of Steel pray about from your perspective?
Elliot S! Maggin: I give all my characters religions. I think I always have. It's part of the backstory. It's part of the process of getting to know a character well enough to write about him or her. Jimmy Olson is Lutheran. Lois is Catholic. Perry is Baptist... Clark - like the Kents - is Methodist.
From: "Denominational Affiliations of Superheroes", posted by Sheridan Voysey on 2 July 2006 on "The Open House (life, faith, culture)" blog website (http://www.theopenhouse.net.au/2006/07/denominational_affiliations_of.html; viewed 19 June 2007):
With all the hoopla this week of the Superman Returns movie, you might be interested to know that almost all our superheroes have some kind of denominational affiliation. Baptist, Anglican, Methodist, Catholic - you'll find connections in the storylines of our best hooded, caped, spandex-covered, super-people...
Superman's other close colleagues have denominational connections too. Jimmy Olson is a Lutheran, Lois Lane is a Catholic, Perry is a Baptist, and Lex Luthor is Jewish (although a non-observant one, as Jews today thankfully remember).