WHEN HE WAS 19 years old, Karol Wojtyla became an actor in the theatrical underground of German- occupied Poland, and considered choosing the theater as his life's calling. By 1960, Wojtyla had become a bishop and professor, but hadn't abandoned his first love. He wrote several plays -- "Our God's Brother," "Radiation of Fatherhood -- A Mystery" and a play called "The Jeweler's Shop" -- under the pen name Andrew Jawien. Published in the Polish intellectual journal Znak, "The Jeweler's Shop" didn't make much of a splash in theatrical circles.

But Wojtyla's boxoffice potential ascended dramatically when he was elevated to Pope John Paul II, and his play was soon translated into Italian and German and produced in Italy and Switzerland.

According to Rev. William J. Byron, S.J., president of The Catholic University of America, "The Jeweler's Shop" is an allegory in three acts about Christian marriage. Several young couples pass a jeweler's window and reflect at length upon an engagement ring. The jeweler, though never seen, represents Christ; his shop, the Catholic church.

The pope's play has never been staged in the U.S. (pity the poor damned soul who gives the Pope a bad notice!). But just before the pontiff embarks on a whirlwind nine-city tour that's more technically taxing even than "Starlight Express," "The Jeweler's Shop" received a simply staged reading Sunday at Loyola University in New Orleans, directed by Rev. Ernest Ferlita, chairman of the drama department. And the play is about to be filmed, under the title "The Goldsmith's Shop," with stars Burt Lancaster and Olivia Hussey.

Another good Catholic, "Les Mise'rables" star Colm Wilkinson (five kids), will take time out from his starring role in "Les Mise'rables" to sing his big number "Bring Him Home" before the Pope's September 16 Mass at Dodgers Stadium. By the way, Actors Equity rules require Wilkinson to return to England at the end of November; he will be replaced in the musical by country singer Gary Morris.

If you happen to catch "The Big Easy," be sure to watch for the screen appearance of the late Charles Ludlam. In his small role as Dennis Quaid's charmingly corrupt New Orleans attorney, he gives a big performance that makes you wish he had done more movies. As founder of New York's innovative Ridiculous Theatrical Company, actor/writer/ director Ludlam invented and performed such artful travesties as "Irma Vep," "Bluebeard" and "Salammbo," among others. His death in May, at age 44, of AIDS complications, was a great loss to contemporary theater.

For some, "back-to-school" also means getting ready to perform in (or sit through) the annual high school play.

According to Dramatics, a monthly magazine for drama students and teachers published by the International Thespian Society, the 10 shows that will be most often produced by high schools this year are: "You Can't Take It With You" (1936); "Bye Bye Birdie" (1960); "Arsenic and Old Lace" (1941); "Guys and Dolls" (1950); "The Music Man" (1957); "Anything Goes" (1934); "Up the Down Staircase" (1969); "Grease" (1972); "The Curious Savage" (1950). High school theater has always been known for its conservative choices -- six of this year's most popular plays were also in the top 10 of 1970-79.

Far too few of us take advantage of the more adventurous dramatic offerings of Washington's universities -- several of them have produced shows that rival or eclipse work by professional theater companies. Here's a glimpse at what's planned for the fall and spring semesters:

American University: "The Real Inspector Hound" (October 8-17), at New Lecture Hall Theater. 885-3420.

Catholic University: "Charley's Aunt" (October 23-November 1); "Rashomon" (December 1-13); "Crimes of the Heart" (January 29-February 7); "The Trojan Women" (March 11-20); and "1776" (tba), at Hartke Theater. 529-3333.

Georgetown University: "The Tempest" (October 22-31); "A Funny Thing Happened on the Way to the Forum" (November 12-21); "An Evening of One-Acts" (December 3-6); "The Fifth of July" (January 21-30); "The Flies" (February 18-27); "Pacific Overtures" (April 15-30), at Stage Three in Poulton Hall. 625-4960.

George Washington University: "A Flea in Her Ear" (October 15-18); "The Hostage" (February 18-21); "The House of Blue Leaves" (April 14-17), at Marvin Center Theater. 994-6178.

University of Maryland: "A Diary of a Madman" (September 17-19); "As Is" (October 20-November 1); "A Chorus Line" (November 5-14); "Power: A Vaudeville" (December 1-13); "Children of a Lesser God" (February 11-20); "The Bacchae of Euripedes" (February 23-March 6); "The Tempest" (April 21-30); "Crimes of the Heart" (May 3-14); at Tawes Theater and Rudolph E. Pugliese Theater. 454-2201.

Bulletin Board: Jeremy Irons has recorded a concert version of "My Fair Lady," playing Henry Higgins to Kiri Te Kanawa's Eliza Doolittle. The recording, on the London label, also features John Gielgud and the London Symphony Orchestra, conducted by John Mauceri . . . Last year, because of the unexpected no-shows of both "Nicholas Nickleby" and "Cats," the National Theater got nuttin' for Christmas. But it looks like the National's stage will be warm this winter -- first up after "Sweet Charity" is "M. Butterfly," a new play by David Henry Hwang, about a French diplomat's affair with a Chinese opera singer . . . A new cabaret space debuts next week: Cabaret Beaux Arts, in the Phillips Collection Ballroom at the Omni Georgetown Hotel, opens September 18. with a double bill. The early show will be Jerry Herman's "Jerry's Girls," followed by a revival of Fred Silver's revue "In Gay Company," which was a hit here in 1983. They've signed an impressive lineup of local performers, including Jeananne Kain, Debra Tidwell, Allison Briner, Melissa Berman and Mark Jolin. The Cafe Beaux Arts is offering pre- and post- show dinners . . . The now-famous farce "No Sex Please, We're British," which opened (to critics' sneers) 16 years ago in London's West End, closed last week after 6,761 performances. The show took in more than $13 million at the box office . . .