Shaken by the first schism in the Roman Catholic Church in more than a century, the Vatican has moved with unusual speed to try to win back followers of renegade Archbishop Marcel Lefebvre.

But it is showing no leniency for those who intend to follow the 82-year-old Frenchman, who consecrated four bishops without papal approval June 30 and was excommunicated.Lefebvre contends the Vatican has broken with true Catholicism by adopting Mass in languages other than Latin and by taking other modernist steps.

Within days of Lefebvre's defiant act, the Vatican firmly stated that it would not tolerate Lefebvre sympathizers, but it made clear that it hoped to persuade them to be loyal to the Roman Catholic Church rather than follow Lefebvre out of it.

It warned that excommunication awaited those who followed Lefebvre and the bishops he consecrated, who also were excommunicated. An excommunicated Catholic cannot participate in the life and sacraments of the church.

Pope John Paul II said Catholics would be committing "a grave offense to God" by joining the archbishop and sympathizing with the traditionalist views of his followers. The renegade movement claims to have millions of sympathizers worldwide, but the Vatican says only about 500,000 Catholics turn to Lefebvre's priests for various church functions.

In an attempt to win back Lefebvre's sympathizers, the pope announced the Vatican would permit wider use of the 16th century Latin Mass. Its suppression by the Second Vatican Council in the 1960s was challenged by Lefebvre and his supporters.

John Paul also appointed a special commission to help meet the "spiritual and liturgical" needs of Lefebvre's followers, while keeping them in the mainstream church.

Cardinal Jean-Marie Lustiger of Paris acted on the pope's words July 3, celebrating the Tridentine Mass in Latin at Notre Dame Cathedral and announcing that Mass in Latin would be said in three churches in Paris each Sunday.

The Tridentine Mass was decreed by Pope Pius V in 1570 and is used by Lefebvre and his sympathizers. In this Mass, unlike the so-called New Mass that followed Vatican II, the priest has his back to the congregation.

"If 12 years ago the church of Rome had allowed Lefebvre to celebrate Mass in Latin, in the Pius V rite, surely today we wouldn't have come to a schism," said Cardinal Silvio Oddi, a conservative Italian prelate.