Those of us who have tuned our televisions to the Rev. Jimmy Swaggart and admired his prodigious capacity to sweat have further grounds for admiration, for we have now seen him bawl. During his recent apologies for that mysterious scortatory adventure that brought him down, his tear ducts produced a steady flow sufficient to soak his face, his shirt and his tie. Yet, notwithstanding my admiration for his art, I will not classify the Rev. Swaggart's performance as an act of contrition. Rather it is a new phase in his charlatanry, a phase of phoniness that is increasingly prevalent, to wit: the rascal reformed and converted into a moral colossus.

The republic abounds with reformed rascals who have transformed past errancies into lucrative careers, for instance: the ex-drug addict, now lecturing others on the evils of addiction; or the ex-Watergate conspirator, now a specialist on the presidency. Presently the Rev. Swaggart will return as a superior authority on vices that many of his paying customers have always been too principled or too intelligent to commit. This goes too far. The Biblical story of the prodigal son is well known, and we all are obliged to forgive repentant sinners; but only in modern America does the repentant sinner promptly hang out a shingle, becoming a consultant on human frailty based on his own history of deviancy.

Americans are especially given to inviting these reformed rascals into the classroom to pontificate to the young, most frequently on what is now called substance abuse. Why educators favor this tactic I cannot fathom. Surely there must be some kids in the audience who note that their celebrated guest would be washing dishes for a living were it not for his adventures in sordidness. A role model who always had the strength to reject the allures of vice is almost certainly a safer bet to persuade the young against folly than the reformed rascal with his lurid past.

The Rev. Swaggart has always been a dubious defender of virtue. The early apostles impoverished themselves by preaching the gospel. Then they got themselves martyred. The Rev. Swaggart got himself a $2.4 million bungalow, limousines and a private jet. All this he acquired by swiveling his hips while reading scripture and denouncing other Bible-pounding humbugs as ''pret-ty lit-tle boys, with their hair done and their nails done, who called themselves preachers.''

I will be persuaded by the Rev. Swaggart's tears of repentance if he does the decent thing and retires from public life completely. He and the other poseurs to virtue who have recently been exposed have given religion enough embarrassing moments and in a time when the only untried emollient for the American spirit seems to be a dignified resort to things spiritual. As Irving Kristol pointed out a decade ago, the American system has made good on its promises of material plenty and political freedom. Yet as all the enrages of our various liberation movements make clear, America has not been able to provide its citizenry with a sense of moral satisfaction. That is the business of religion or philosophy.

It is an absolutely capital idea to infuse ethics into our politics, but it is an even better idea to keep religion out. Politics and religion are provinces abounding with frauds. The fraud who might prevail in both provinces will be an unsurpassed menace to freedom and to much else, for he will be claiming the sanctions of God and the sanctions of Caesar. This is why the political campaigns of the Rev. Jackson and the Rev. Robertson deserve so little encouragement. The pretensions of ordinary politicians are oppressive enough; the pretensions of the political divine would be intolerable.

Conservatives in Washington such as Richard Viguerie are now welcoming the Rev. Robertson as the conservative leader of the future, the next Ronald Reagan. Well, boys, in the words of the poet S. Goldwyn, ''Include me out.'' There is a recklessness and a low-down meanness about the Rev. and some of his associates that are best kept out of 1600 Pennsylvania Avenue.