France is preparing a triumphal welcome for Pope John Paul II in Paris Friday in an outpouring of enthusiasm that contrasts starkly with the decline in religious practice in this traditionally Roman Catholic country.

The Polish-born pontiff, 60, faces a crowded schedule for his four-day visit, during which several million people are expected to flock to see him. It will be the first time a pope has visited France since 1804, when Pope Pius VII officiated at the crowning of Napoleon.

Although the pope will celebrate three public masses, ride through the streets of the capital and address French Catholics on several occasions, perhaps his most significant engagement will be behind closed doors at suburban Issy-les-Moulineaux.

There, on Sunday, in a speech to the French Bishops' Conference, Pope John Paul will attempt to soothe what he this week called the French church's "growing pains."

Church statistics show that 45 million of the 53 million people in France were baptized as Catholics, yet opinion polls indicate that only 12 to 17 percent of them attend church regularly, compared with 35 percent two decades ago. About one-third of young people say they do not believe in God. d

The number of young men becoming priests is dropping too. There are 36,000 priests in France, but their average age is 55, younger men are not coming forward to replace those who die.

"Since 1969, I have ordained eight young priests in my diocese," Bishop Gabriel Matagrin of Grenoble said this week. "Three of them have since got married and a fourth killed himself."

Pope John Paul is expected to tell French bishops to show more dynamism in spreading the gospel, encouraging priestly vocations and opposing birth control, abortion and materialism, church sources said.

Use of artificial contraceptives has become widespread in France in the past 10 years and in 1974 the government pushed through a bill legalizing abortion, the first predominately Catholic country to do so.

The pope also has to take account of the split within the French church between the majority of Catholics who accept recent liturgical reforms and outspoken traditionalists led by rebel archbishop Marcel Lefebvre.

In a conciliatory gesture, Lefebvr has put off for two weeks a Latin mass he planned to celebrate on Sunday at the Paris church of St. Nicolas du Chardonnet following the Tridentime rite outlawed by the Vatican.

Although Lefebvre will avoid an open clash with church authorities during the pope's visit, the problem created by his supporters' three-year illegal occupation of the church has still not been resolved.

The pope's visit has political as well as religious implications. At Orly Airport, the pontiff will be welcomed by Prime Minister Raymond Barre. He will be greeted on the Champs Elysees by President Valery Giscard d'Estaing and will be received at City Hall by Paris Mayor Jacques Chiac.

Representatives of all political parties have been invited to services Friday in the Cathedral of Notre Dame and to a reception Saturday at the Elysee Palace. The Socialist Party has allowed each Socialist deputy to decide whether to accept or decline the invitations.

The Communist Party, which has called the pope's visit "a great event for our country" will send a delegation led by Maxine Gremetz, central committee secretary and head of external relations.