The pope, whose visit to Poland has been occupying so much attention, is less conspicuously in the news in respect of his forthcoming visit to America in September. But there is much freight in that visit, and not only American Catholics but observers of trends in the largest Christian communion in the world are intensely curious about what will happen during that trip, which will begin in Miami and terminate in Detroit.

The reason for it is that Pope John Paul II, universally admired as an individual, is deeply controversial. During his papacy he has been adamant on a few matters that have to do with the general understanding of what is needed in order to advance the goals of ecumenicism.

Herewith a word or two about one apparently insignificant item which, however, looms large in the enthusiasm of many Catholics and not a few Protestants who have for centuries been fellow travelers of the long-standing Catholic tradition of using Latin in the Sunday liturgy.

The question is of transdenominational interest because the use of Latin in the liturgy, over the years, was not only a special identifying signal of the Catholic Church. It was also, in a curious but not entirely surprising way, something of a Bureau of Weights and Measures for the entire Christian community. Here is a not-at-all-dirty little secret about Catholic orthodoxy, namely that dogmatic constancy by the Catholic Church is something that, though not emulated by many Christians, has been secretly admired by many of them; even as the easygoing and pleasantly bibulous family admires Aunt Bessie the teetotaler and is horrified to find her, one Saturday night at dinner, ordering a stinger after dessert.

The obsession with ecumenism led many Catholic bishops to go much further with Vatican II of the 1960s than was ever intended by its architects. The principal evidence of this has been the death of the Latin Mass. Suddenly it ceased to exist, notwithstanding that the relevant document in the 1963 ''Constitution on the Liturgy'' of Vatican II reads (sec. 36), ''Particular law remaining in force, the use of the Latin language is to be preserved in the Latin rites.''

One or two recent polls (by Gallup, 1984; by Hoge et al., Sociology Department, Catholic University, 1985) reveal that one-half of America's 52 million Catholics want the opportunity to attend a Latin Mass conveniently on Sundays. They feel, on deep questioning, that a steady diet of vernacular Masses leads to a loss of the sense of the sublime, of the mysterious and supernatural, leading to a diminution of the sense of the presence of God, who is -- well, different from the Rolling Stones.

Beautiful prayers can be and are written in the idiomatic mode, but there is a craving by many for the kind of remove that made the King James English translation (''Why standest thou afar off, O Lord? Why hidest thou thyself in times of trouble?'') poetically resonant in a way that ''Come on into my tent, God'' is not. ''Corpus Christi custodiat animam tuam'' means, ''May the body of the Lord look after your soul.'' But said in the first way, there is spiritual foreplay that doesn't always stimulate, said in the vernacular.

The public misapprehension is that Big Deal questions addressed by Big Deal kings, presidents, prime ministers and popes treat only Cold Wars, nuclear bombs, starvation, pestilence and sex. But the pope knows that we do not live by bread alone, and there are those who hope that, having cast bread out into the waters, their hunger will be mitigated. So look for a sign of life, in September, not only from the theological trendies, but from those who seek to rise from the catacombs.