ANKENY, IOWA, FEB. 3 -- Bypassing the biblical injunction to "turn the other cheek," the two most overtly Christian presidential campaigns have launched a bitter battle of mud-slinging and rumor-mongering to win support from born-again Christians in this state's Republican caucuses.

In their fliers and phone banks, backers of former television evangelist Pat Robertson are charging that Rep. Jack Kemp (R-N.Y.) is unworthy of Christian support because of his policies and personal life. Meanwhile, Kemp supporters and various anonymous sources are distributing literature charging that Robertson's politics and theology violate scriptural teachings.

This week, for example, someone stuffed the faculty mailboxes at Faith Bible College here with a photocopied flier suggesting that Kemp's support for a gold standard underlying international currencies is an un-Christian position. The flier was signed "Students for Robertson."

Some Des Moines-area Baptists received a document saying that Robertson's tactics in the Michigan Republican campaign violate biblical laws enunciated in Chapter 13 of Paul's letter to the Romans. The paper was not signed, but Kemp aides acknowledge it was the work of a Kemp supporter.

In southwest Iowa, a conservative bastion, some Republicans say that a local Robertson campaign worker has been telling born-again Christians that Kemp has not been a faithful husband. Asked about this, the Robertson backer, Russell Rogers, replied, "There's a lot of junk like that flying around, and I don't know who's saying what about anybody."

In Page County, on the Missouri border, the animosity between competing groups of Republican Christians has gotten so heated that GOP Chairman Dennis Parrot has ordered a cease-fire. "I've told these people to knock it off," Parrot said. "I tell them that Jack Kemp and Pat Robertson will be gone once the caucuses are over, but we have to live with our neighbors down here for the rest of our lives."

Parrot is supporting Sen. Robert J. Dole (R-Kan.) for president.

The increasingly nasty Kemp-Robertson conflict reflects the importance of born-again Christians in Monday's Republican caucuses, when the two will be battling for the role of chief conservative alternative to the GOP front-runners, Vice President Bush and Dole.

The born-again population has been an important factor in Republican politics here in the past. This year, though, it seems that religious concerns will loom larger. In a sermon last Sunday, for example, a prominent Des Moines minister, the Rev. John Palmer, senior pastor of the First Assembly of God Church, told parishioners to apply a "biblical litmus test" when choosing a presidential candidate.

Officially, both campaigns say that they deplore the attack materials that have spread. "It's amazing how much of this junk there is out there," said Marlene Elwell, Robertson's Midwest campaign director. "We wish there weren't any, on either side."

Elwell said the anti-Robertson literature and rumors "definitely come from the Kemp people, or at least we have a pretty good idea that's who it is."

Elwell said Kemp backers are probably behind a 15-page compilation of Robertson quotations that has been mailed to evangelical Christians by the "Coalition for Biblical Renewal." The document purports to show that Robertson is a practitioner of "New Age" theology, derived from Oriental cults. Robertson denies any connection with the "New Age."

The Kemp campaign, in contrast, says Robertson's people have told many Christians that Kemp's advocacy of a gold standard conflicts with scripture.

Kemp and Robertson are showing voters long lists of born-again ministers who support them. And Dole on Tuesday announced formation of "National Coalition of Evangelicals for Dole."