Raising the issue of a US envoy to the Vatican, again. Opponents of the US having an ambassador to the Holy See have appealed to the Supreme Court to keep the now-vacant post permanently so

DOES the United States really need formal diplomatic ties with the Vatican? And does the appointment of an ambassador to the Holy See constitute a breach of the First Amendment's guarantee of separation of church and state?

The answer to the first question is probably ``no.'' The second issue is still in the courts. But so far, the judiciary has seen no constitutional bar to this arrangement.

Over vocal protests from many religious groups (among them Protestant, Roman Catholic, and Jewish) and civil liberties organizations, President Reagan appointed William Wilson, a Roman Catholic, as ambassador to the Vatican early in 1984.

Mr. Wilson, a California businessman and long-time confidante of the President, resigned the post last spring in the aftermath of reported embarrassment inside the administration over the ambassador's unauthorized trip in March to visit Libyan leader Muammar Qaddafi.

Since then, the post has been open. And opponents of formal ties have renewed their efforts to urge the White House to leave it that way. In fact, a coalition of church-related groups and advocates of religious rights -- led by Americans United for Separation of Church and State (AU) -- has asked the US Supreme Court to strike down the US-Vatican relationship as unconstitutional. It is not known whether the high tribunal will even take the case, much less decide it.

In its brief, the plaintiffs charge that the ambassadorial ``arrangement'' violates the Constitution by conferring special privileges on one religion and entangling the government in church affairs. And it asks the justices to overturn lower federal court rulings denying the plaintiffs' legal standing to challenge the diplomatic exchange.

AU executive director Robert L. Maddox says: ``We strongly believe that Americans have a right to take this matter to the bar of justice. The First Amendment forbids the government to establish a special relationship with one religious faith. The Supreme Court has a duty to correct the Reagan administration's mistake in exchanging ambassadors with the Vatican.''

But the lower courts have seen it differently. The Third Circuit Court of Appeals, in upholding another federal court, dismissed the charge that a formal diplomatic tie with the Vatican gives the Roman Catholic church ``a form of access to the Executive branch superior to that which is available to other religious organizations.''

It also threw down the argument that the existence of such a relationship ``subjects them [the administration] to pressure to conform to government policies of which the Roman Catholic church approves.''

The appeals court said that a communication to the President through a diplomat would not be any more effective than ``a letter from the plaintiffs or a luncheon meeting between the President and a prominent cleric.'' Further, it ruled that the challenging coalition offered no ``explanation as to why the delivery of a statement of church position through a diplomat would be any more influential on the plaintiffs' conduct than would be the publication of the same statement in the national press.''

Generally, the Reagan administration has defended the arrangement as a diplomatic rather than a religious tie. It explains that the Vatican, as a sovereign state, is to be distinguished from the Roman Catholic church itself. Also it has stressed that, traditionally, the courts have not interfered with the diplomatic activities of the Executive branch.

The controversy has spurred some recommendations that the appointment of a non-Catholic to the Vatican post would quiet some concerns about religious favoritism.

AU's Reverend Maddox says that this would not solve the problem. Further, he points out that ``Article VI of the Constitution forbids any religious test for public office.''

Wilson was the first ambassador to the Vatican since 1867, when Congress cut off funds for the support of an American legation in what were then known as the Papal States. Since 1939, presidents have designated ``personal representatives'' in the Vatican. In 1951, Harry S. Truman sought to appoint an ambassador. But he withdrew the nomination after strong public protest.

Perhaps it is now time to end the religious wrangling and return to the designation of personal representative.

A Thursday column