THOSE with a perspective on the church-state issue are perplexed by the way Ronald Reagan seemed to have it both ways: He was able to win both the Protestant and Roman Catholic vote while taking positions relating to religion that in years past could have cost him the support of one or both groups.
Could you imagine John F. Kennedy coming out for tax credits for parents with children in parochial school and being elected President? Kennedy dissipated this anxiety by hueing to a nonreligious line on most issues - although some observers interpreted his Vietnam involvement as stemming from his religious affiliation.
A New York Times/CBS poll showed that the only group that reacted negatively to Mr. Reagan's stands on religion were Jewish voters. Early in the campaign, his generally pro-Israel position, together with the strong economy, was winning a lot of voters to his side. Also many Jews felt that candidate Mondale had failed to suitably condemn the Rev. Jesse Jackson for what they deemed to be anti-Semitic comments.
But Jewish voters became alarmed by what they saw as a cozying up to the founder of the Moral Majority, the Rev. Jerry Falwell. In the zeal of Mr. Falwell and fundamentalist Christians many Jews saw the possible imposition of laws that would infringe on the rights of others, and themselves. The President's support of prayer in schools bothered many Jewish voters. So they supported Mondale on election day by 62 to 32 percent.
What about the millions of Protestants who are not in the fundamentalist groups? Many are still opposed to anything that would weaken church-state separation - whether in the direction of helping Roman Catholics or some Protestant religions.
Yet there was little sign of defection by these Protestants from voting for Reagan in the final vote. White Catholics divided 58 percent to 41 percent for the President. Born-again white Christians, who once gave their votes to Jimmy Carter in 1980, backed Reagan by an 81 to 19 percent margin. And the other white Protestants voted for Reagan, 69 to 30 percent.
I've made a an effort to talk with voters who were unhappy with Reagan's religious stands but who still voted for him. These conversations and a review of voting patterns over the last generation along with other data have caused me to come to these conclusions:
* For a number of reasons, separation of church-state is not the burning issue it once was. But people who felt passionately about it - and who thought Reagan was treading outside of his prerogatives - thought the economy was the important issue which overrode these negative feelings.
* Many Protestants who cited Reagan's sending an envoy to the Vatican and his ''getting too close'' to high-level Catholic clerics, said they voted for Reagan simply because they couldn't vote for Mondale. Other Protestants who didn't like Reagan's Falwell connection, his school prayer stand, or the anti-abortion legislation were providing a similar answer.
* Voters who opposed Reagan on what was called the ''religious issue'' were pulled back to supporting the President because they trusted Mr. Reagan.
Those who trusted Reagan took the position that they trusted him not to go too far - whatever that meant. They also took comfort when he declared, near the end of the campaign, his all-out support of separation of church and state.
For whatever reasons church-state separation didn't do much to shape this last presidential election.