Deep thoughts about church and state come easy. So liberals and conservatives alike make a fearful racket over the political role played by religious groups such as the Moral Majority.

But midst the tumult, serious questions go unanswered. How important are the religious groups in deciding elections? And how revelent is the church-state issue to choosing a president?

The standard liberal litany begins with the constitutional prohibition against an established religion. It goes on to the tax-exempt status accorded church groups. It then recites horrible example after horrible example of funds raised, voters mobilized and endorsements given.

There follow remarks about the vulgar, ofter irreligious quality of electronic evangelism. Then comes the final condemnation of the menace to Liberty, the Republic and the Constitution.

The conservative defense starts with a set of questions. Who, after all, began smuggling moral preferences into politics? Who presses to legalize abortion, and then have the federal government pay for it on demand? Who claims equal rights for gays? And for lesbians? Who pushes for recognition of the drug culture?

To answer all of these questions, of course, is the very liberals who slam the evangelical groups. What the liberals are seeking, in other words, is a political monopoly. At best, there is a double standard at work. At worst, the liberal clique seeks a protected position to shape behavior in ways that offend the majority and (in the extreme argument) undermine the national spirit.

The very vigor of the debate falsifies the most dire warnings. Neither side is on the verge of total victory, and rival claims have to be examined case by case.

The power of evangelical politics is, to begin, highly localized. "It comes in clusters and in clumps," said Linda Sutherland, a public opinion expert who works for political scientist Richard Scammon. In particular, large numbers of people in, or from, rural parts of the South and the West can be mobilized against recent trends toward moral permissiveness.

"Against" is the operative word. The political strength of the evanglicals is largey negative. Their hit lists pack a punch. They can cause genuine trouble when they gang up on certain candidates in certain areas.

A notable example is Rep. John Buchanan, a Baptist minister with liberal views on race, who lost his bid for reelection last month in the Republican primary for the Sixth District of Alabama, Dick Clark, the Iowa Democrat who lost his Senate seat in 1978, is said to be another case.

But John Culver, Iowa's incumbent Democrat senator, faces the same kind of opposition. Unlike Clark, he is meeting it head-on, and not doing so badly.

One reason the head-on fight can win is that the evangelicals, while strong in opposition, have a hard time finding attractive candidates. Frank Church, the veteran Democratic senator from Idaho, for example, is high on the evangelical hit list. But whatever his voting record, Sen. Church and his wife, Bethine, epitomize the folksy virtues. His Republican opponent, Rep. Steven Symms, has connections with the silver speculation of the Hunt brothers that seem to stamp him as a bit of a rascal.

The same kind of miscasting complicates -- and probably dooms -- the effort to get House Majority Leader Jim Wright in Fort Worth. As Sen. Culver points out with some glee, one politician who ranks 100 percent in the vote ratings of the evangelicals is Richard Kelly, the Republican congressman who lost his primary battle in south Florida because of deep involvement in the Abscam scandal.

On the national level, moreover, the evangelical factor just doesn't cut. Ronald Reagan's visit to the convention of the Moral Majority in Dallas a month ago may do him some good. But a Gallup poll shows that Jimmy Carter has the evangelical vote locked up, and it is not thinkable that a candidate who clashed openly with the basic preferences of the Majority could win the nomination by the Democrats or the Republicans.

Nor does the president play much of a role in affecting most of the issues, issues called "moral." The Supreme Court and Congress dominate on such matters as school prayer and abortion. Presidents have more important business. Indeed, there is something morally irresponsible in making a fuss about evangelical politics and thus further diverting attention from the true issues -- especially the economy -- that have not yet come front and center in the 1980 campaign.