Under the unwritten tribal rules of the U.S. Senate, senators are normally treated with kid gloves when they testify before one another's committees. They typically read a statement prepared by a staff member, and hurriedly depart after being congratulated for their wisdom, foresight and the beauty of their home state.

But when Sen. Roger W. Jepsen (R-Iowa) yesterday proposed abolishing the Federal Election Commission before the Senate Rules Committee there was no such chumminess.

Instead, Jepsen found himself subjected to a biting, sarcastic attack after he suggested the committee be guided by "two overriding principles"--"simplicity and faith"--as it considers an overhaul of the nation's election laws.

"Recognize that the simplest law can very often be the best law. People have been trying for years to re-invent the mousetrap and have found this an exercise in futility," he told the committee. "I firmly believe that returning to a simpler election law will go much further in restoring the public's confidence in their elected officials."

Sen. Wendell Ford (D-Ky.) led the charge. He challenged Jepsen's facts, how well the Iowa Republican had thought out his proposals, and his blind faith in the goodness of politicians.

"I know you are a deeply religious man, but doesn't it say somewhere in the Bible that faith without good works is dead?" said Ford. He then launched an all-out attack on a Jepsen proposal to have the federal government pay for the cost candidates incur in reporting who they receive campaign donations from.

"Isn't that public financing?" Ford asked. He then went into series of questions about where the government, in these days of budget cutting, could find money to do this.

Jepsen was visibly taken back. He fumbled. He dodged. He evaded Ford's questions with statments like, "I'd have to think about that a while, senator," and, "That's a question that is being debated by a lot of people." As for himself, Jepsen said he hadn't expected to join in such a debate this particular day.

His testimony was part of the conflicting advice the committee heard on the elections commission. Senate Minority Whip Alan Cranston (D-Calif.) and Fred Wertheimer, president of Common Cause, the self-described citizen's lobby group, said that despite its faults the FEC is needed to ensure a fair and nonpartisan enforcement of election laws.

Each, however, proposed major changes in these laws. Cranston suggested a reform to make it easier to run against wealthy opponents. Under current law, a candidate can spend an unlimited amount of his own money. To overcome the advantage this gives to multi-millionaires, he proposed that once such a candidate donates $35,000 of his own money, other contributors could donate unlimited amounts to the opponent.

He said FEC records show that 21 candidates put between $100,000 and $500,000 of their personal funds into Senate campaigns during the 1980 elections.Five other Senate candidates spent more than $500,000 of their own money.

Wertheimer proposed that a ceiling be placed on the amount any Senate or House candidate can receive from political action committees during any election. He said the amount of money such committees donate to congressional campaigns has increased from $12.4 million in 1974 to $55 million in 1980.