No more uncongenial task, except voting against President Reagan's pet weapons systems, faces members of Congress than passing judgment on one another.

But they do understand that while they can duck and weave on cosmic questions of war and peace and shamelessly shelter themselves in "compromises," "packages" and "bipartisan consensus," on matters of individual morality they have no place to hide.

The two cases that had been laid before them by the House Committee on Standards of Official Conduct had a fearful symmetry: one involved an ultra-right Republican conservative, the other an unflinching Democratic liberal; one sexual transaction was "straight," the other homosexual.

In the end, ideology did not matter. Nor did the fact that they were dealing officially, for the first time in their history, with homosexuality.

The vote did not reflect anything about tolerance or intolerance of "alternative life styles."

The House voted to censure both Rep. Daniel B. Crane (R-Ill.), Moral Majoritarian, midwestern dentist, father of six, indefatigable moralizer and Protector of the Family, and Rep. Gerry E. Studds (D-Mass.), the brainy, disdainful, sardonic scion of an ancient, lustrous Massachusetts clan, who admitted to his colleagues in an unprecedented floor speech last Thursday that he is homosexual.

Both men (and they have nothing else in common) had, in different ways, made it easy for their colleagues.

For everyone who was repelled by Crane's abject act of contrition on national television--his teary plea for forgiveness with his stony-faced wife by his side and his 3-year-old daughter in his arms was enough to give repentance a bad name--there were perhaps twice as many who were genuinely shocked by Studds' claim on the House floor that the 17-year-old male page, whom he seduced after copious infusions of vodka and cranberry juice, was "an adult" and that the relationship, continued on a trip to Europe, was "consensual."

If ever there was a congressman who seemed able to beat the homosexual rap, it was the witty, articulate Studds.

He had fans in neighborhood bars and in rarefied liberal circles. His fishermen constituents in New Bedford were proud of his role in setting the limits of fishing rights. His suburban liberals applauded him for his incisive opposition to the nuclear buildup and to war in Central America.

His constituents were indignant when the undisputed allegations were made public.

They were, by an overwhelming majority, indignant not at Studds but at Congress for telling them what they already knew. With few exceptions, mainly mothers of sons, who quarreled with Studds' designation of a 17-year old as an "adult" and observed that he had made sexual advances to two other male pages, they said they felt that Studds' sexual preference was his business--and not theirs. And besides, as Studds said, it all happened 10 years ago.

With Studds' strong support at home and Crane's public prostration, all seemed in order for the vote of "reprimand" recommended by the ethics committee. But gray-thatched Rep. Newt Gingrich (R-Ga.) demurred. To the surprise of all, and the discomfiture of many, he announced that he would introduce a resolution to expel Crane and Studds from Congress.

He explained his reasons to a wholly attentive House.

Studds' refusal to say that he was sorry was more than Gingrich could handle. He could not differentiate between Studds and Crane, whom he did not mention. Crane's partner in a summer fling was, from her testimony, entirely willing.

But both cases involved exploitation of teen-agers and abuse of office. GOP leader Rep. Robert H. Michel (Ill.), who said he felt that the move for expulsion was gaining strength by the moment, apparently felt forced to stand up and propose censure for Crane, who was first in the dock. For a partisan, it went against the grain. But to do otherwise would have meant further delay, more talk in the country and more shame on the House.

Crane sat slouched down in an aisle seat on the Republican side with his brother, Rep. Philip M. Crane (R-Ill.). When Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) summoned him to the well, he walked with his hands folded before him, like someone bound for the stake. He turned his woebegone face to his peers.

Studds was surrounded by sympathetic members of his delegation. When his turn came, he walked erect from a front-row seat, held his hands behind his back and kept his eyes on the speaker's face, as if it were still a private matter.

Then he went out onto the steamy Capitol grounds and spoke to the press, sardonic and defiant to the end.

"All members of Congress are in need of humbling experiences from time to time," he read from a prepared statement.

Humbling they may need, but humiliation is still not popular.

They can eliminate the risk by eliminating, as Rep. Bill Frenzel (R-Minn.) sensibly suggested, the preposterous page system. But for once, the "long-term solution," so often repaired to in sticky situations, had no appeal.