The recent baptism was the 17th performed by the Rev. Mikhail Nutskovski since the Ukrainian priest arrived last September in this primarily Orthodox city in southern Russia to serve at the Roman Catholic Church of The Last Supper. But while the church claims more than 150 members, the baptisms, as well as all other services, take place in a small, chapel with low ceilings in the basement of the rectory.

The city's Roman Catholics gather underground because the main church building remains unfinished. Set among the trees in a large suburban park, the red brick structure has stood silent and unattended since 2000, when city authorities ordered the Catholics to halt the construction they had four years earlier. The reason remains in dispute.

Nutskovski said the work stoppage is one item in a long list of roadblocks that local and national authorities, in league with the Russian Orthodox Church, have used to prevent the spread of Catholicism throughout Russia in what some Catholics call a campaign of discrimination. Numbering about 600,000, Catholics are a distinct minority in this country of 143 million.

''We feel a very unfriendly attitude toward the church from the authorities here,'' Nutskovski said. ''They are so hard to understand. They say we can't build because we don't meet requirements, but how can we fix the problems if we can't build?''

Local officials tell a different story. They say Nutskovski is a troublemaker who is trying to build a church without city approval while hiding behind allegations of discrimination.
''This is the tricky game of the Catholic Church here,'' said Vitaliy Brezhnev, the Rostov regional government official who handles religious relations. ''They like to create scandal.''

A rift between the Vatican and the Russian patriarchy has existed for centuries. In the past year and a half, the tension has escalated.

As communism and the Soviet Union's official policy of atheism fade further into the past, many faiths have made inroads into this almost exclusively Orthodox country. In January 2002, the establishment of the first four Roman Catholic dioceses in Russia provoked accusations from an Orthodox official that Catholics were trying to poach members.

This spring, the creation of two dioceses in the former Soviet republic of Kazakhstan sparked more criticism and hardened the position of the head of the Russian Orthodox Church, Patriarch Alexy II, against a papal visit to Russia any time soon.

The Church of the Last Supper, which is designed to seat 3,000, towers above the rest of the two-story compound. But the paint-splattered front entrance is locked, and the doors sit three feet above the ground with no stairs climbing to meet them. Dilapidated wood scaffolding leans precariously against the bare concrete front of the building, and piles of sand and trash litter the front yard.

Nutskovski said local officials have threatened to evict the church from its present location, land that was donated by the regional government in 1992 as reparations for the original church, which was burned down by Stalinists in 1952.

But the priest said his biggest fear is that he will be forced out of Russia. Since January 2002, six Catholic priests have either been deported or denied reentry. One was Nutskovski's predecessor, the Rev. Edvard Mackiewicz, who left in September for a trip to Poland and never returned. He was stopped at the Poland-Belarus border by Russian guards, declared a persona non grata, and denied reentry.

Brezhnev, the Rostov government official, said Mackiewiczwas not allowed to return to his parish because he was a troublemaker and said he suspected that the other five exiled priests were ''lawbreakers.'' While the Russian government calls the six isolated cases, Nutskovski views his required quarterly visa renewals with apprehension.

''There is a permanent risk every day that I can be sent away from Russia,'' he said. ''As a senior priest, I planned to be here for several years, but now I must worry every three months.''

A parishioner, Vladislav Donskoj, 72, said he believes Mackiewicz was denied reentry because the charismatic priest attracted newcomers to the church.

''If a person becomes very active and attracts the attention of authorities, he will have trouble,'' Donskoj said from the church's gravel courtyard, surrounded by piles of expensive bricks waiting to be laid. ''The government doesn't like non-Orthodox religions.''

But the pastor remains cautiously optimistic about the future. Nutskovski said he hopes a recent meeting between a Vatican ambassador and a representative from the Rostov governor's office may help smooth relations.

''The main goal is to explain to people that they shouldn't be looking for differences among themselves. Instead, they should be seeking common ground,'' he said. ''I hope the officials will soon understand that the Catholics here are Russian citizens.''

The overflowing Sunday crowds in the underground chapel and the frequent First Communion and baptismal ceremonies point to a resilient base of followers here.

As the baptism came to a close, parishioners prayed aloud in unison. Some closed their eyes and repeated the familiar words by heart. Meanwhile, the infant, dressed in her new baptismal gown, slept peacefully in her mother's arms.