The forum for the rivalry is not the pulpit or church bulletin, but the website of ICANN, the corporation that oversees the internet address system and now wants to expand it beyond the usual .com, .org or .net domains.
When ICANN began accepting applications for new names early this year, bids came for extensions such as .catholic, .islam and .bible. Not far behind were critics who challenged many applicants' right to monopolise those and other religious terms.
"I respectfully ask you not to award .bible to a bunch of hardcore Bible-thumpers," wrote one critic of an application by the American Bible Society to manage that extension.
Questioning a Turkish IT company's bid for the .islam domain, Fahd Batayneh of Jordan's National Information Technology Centre asked how it could ensure no pornographers or Muslim extremists would use names with this ending?
ICANN (www.icann.org), the Internet Corporation for Assigned Names and Numbers, is accepting comments on these and other applications for another month and will then evaluate the bids for new extensions, known as top level domains (TLDs).
First results are due next summer. A group awarded a TLD can manage that domain exclusively, renting out addresses that use its extension and rejecting bids it considers unsuitable.
The religious problems facing this 21st century project are as old as the schisms and heresies that have haunted faiths for ages. Who speaks for Islam? Does the Vatican have a monopoly on the word "catholic"? How should one interpret the Bible?
"I don't think I can solve issues that have been going on for centuries," Akram Atallah, interim head of ICANN, told by telephone from its Los Angeles headquarters.
"Our goal, at the end of the day, is to provide innovation in the domain name system."
Website owners are now restricted to a few dozen TLDs such as .com and country code domains such as .co.uk. Many of the 1,930 applications for new TLDs came from companies, including internet giants such as Amazon and Google.
If there are rival bids for the same TLD, ICANN has panels of experts to consider legal, financial and technical factors in making the decision to award a domain name. A dispute resolution process exists if an losing applicant disagrees.
But there won't be geeks consulting Gospels to decide who can have a TLD such as .church.
"We don't look into whether the Vatican has the right to the .catholic name," Atallah said. "Hopefully, the process will get to a conclusion that is satisfying to the majority."
Saudis oppose, Christians squabble
Saudi Arabia, the birthplace of Islam, seems to see no hope of a consensus on religious TLDs and opposes them all.
Its Communications and Information Technology Commission filed 163 comments, opposing not only TLDs with Muslim terms such as Islam, halal and Shia but also Catholic and Bible.
It also criticised bids for sex, gay, wine, virgin, dating, porn and other terms that go against its strict moral code.
The Vatican's application for exclusive use of .catholic drew criticism from members of several Protestant churches who also use the term, which comes from the Greek for "universal".
"This request is a move by a powerful group to squelch the voices and rights of other Christians," wrote Dave Daubert, pastor of Zion Lutheran Church in Elgin, Illinois.
Some comments asked if the large Life Covenant Church, based in Oklahoma, would share the.church name it applied for with other Christians who did not hold its evangelical beliefs.
"If something as basic as the Ten Commandments can't be agreed upon, how can the TLD be operated fairly?" one asked.
The American Bible Society would share the .bible domain with "individuals and groups who, regardless of faith, have a healthy respect for the Bible," spokesman Geoffrey Morin said.
Clerics aren't the only ones trying to get into the game.
AGITSys, an Istanbul-based IT company, said it wanted to create "a quality online space for the Muslim faithful" with domain names such as .islam and .halal and would allow Sunnis, Shi'ites and members of other schools of Islam to use it.
"They didn't consult anybody in the Islamic community," said Batayneh from Jordan. "This application should have come from the Organisation of Islamic Cooperation in Jeddah."
Some religions seem to have kept out of the fray entirely. There were no applications for .buddhist, .hindu or .jewish.