Bottles and trash litter the pavement at 14th and P streets NW. Grates and iron bars make patterns on the fronts of garishly painted buildings and various street people stand day after day as if frozen in an urban still life.

This colorful intersection seems an unlikely haunt for a Baptist minister. But it is here that the Rev. Joao (pronounced Ju-all) Petrovitch, 35, spends his weekdays mending mufflers--when he is not ministering to his flock in an unusual combination of callings.

On Sundays, he can be found in a three-piece suit with a Bible in his hand, leading the Brazillian congregation of Georgetown Baptist Church. Weekdays, he is the muffler man again, dressed in greasy work clothes, with his welding torch at the shop he runs with his gregarious brothers, George, Paul and Pedro.

He is one of four brothers, Brazilian-born of Russian descent, who operate the Petrovitch Auto Repair Shop on the northeast corner of 14th and P, a business highly rated by local consumer guides since its opening in 1974.

The Petrovitch family has been in the business for more than 25 years. Their father, Jan, opened the original Petrovitch repair shop in 1958 in Sao Paulo, Brazil, after completing his training at the Ford Motor Co. plant there.

The sons joined the father's shop when they turned 16. "Our father always said to us, 'It's not only for the money,' " George, 47, recalled, in an English accented with a trace of his Russian heritage. " 'When you go work, you work with love . . . when you do a job, you do for you, not for somebody else.' "

The lesson aparently held: The brothers perform as if they love their work, and the steady volume of business suggests customers are willing to pay for the quality of work they provide, or as Pedro puts it, "We are very good, but we are not very cheap."

The atmosphere in the busy auto shop is at once festive and international. Mercedes-Benzes, Hondas and Cadillacs sit silently on pedestals above a backfire of laughter, jokes, friendly banter and loud Latin music blaring from Radio Mundo, a local Spanish Language station. . One wall is covered with license plates from every state in the nation and, of course, Brazil.

George, eldest of the four, manages the garage's body shop. He is especially talkative and will offer advice on topics ranging from marriage to wrestling. In Brazil, he was known as the "Russian Lumberjack" on the professional wrestling circuit. Wrestling was his part-time job while he served in the Brazilian army as a sergeant for 18 years.

Although he acknowledges a successful wrestling career, George is not boastful. "I lose, I win, I lose, I win; Just depends on how many bottles I have before going to the ring."

One wall of George's small glass office at the back of the shop is lined with signed photographs of him, rubbing elbows with Mayor Marion Barry, Joe Theisman, Billy Graham and other notables.

Paul, 39, half-owner and comanager of the garage, was the first brother to arrive in this country, in 1962, looking for the "good life." In Brazil, he worked as a commercial pilot.

Now, he prefers to keep his feet on the ground, spending time at his Cabin John home with his wife and two children. His wife, Charis, is a Californian who works as a hospital anesthesiologist, and Paul cracks with typical Petrovitch irreverence, "She's an M.D., and I'm a D.M., Doctor of Motors."

Pedro, 38, also a half-owner and comanager, is a workaholic by his brothers' accounts. He "runs the show," they said, handling all the paperwork.

"My hobby is work," said Pedro, whose wife, Carol, a dental student, is the sister of Paul's wife. Even in his work the family humor prevails. "Lady, your car needs a new car," he told one customer.

Family legend has it that Jan Petrovitch's father, who had emigrated from Russia to New York, later sent for his wife and children in 1924, but the steamer carrying them landed in Brazil.

Shortly thereafter, news of the father's death reached the family in Brazil, and having no reason to move on, they located a small Russian population and a Baptist Church and stayed. Jan Petrovitch grew up to marry a zealously religious Russian immigrant, whose uncle had arranged the union.

Gina Petrovitch encouraged her eight children to pursue an interest in music, often playing guitar and singing to the family. It was while she was pregnant with Joao that his life's work was determined. He grew up hearing of his mother's conviction then that he would be a great preacher.

Joao, a usually quiet, reserved man in contrast to his extroverted brothers, is devoted to his congregation of about 40 Portuguese-speaking members from Angola, Brazil and Portugal. He preaches with an intense fervor at his 1 p.m. Sunday services in the lower auditorium of the church at 31st and N streets NW.

"He puts everything into it," said Jacy Santos, an active church member who is responsible for introducing Joao to his present congregation.

Joao's wife, Ruth, tends the nursery at the church, while he leads the people he calls his "only children" in song and praise. Often he and his brother George will play mandolin during the service.

Before coming to America, Joao had been the pastor of The First Baptist Church of Campo Limpo in Brazil for three years, working at the same time in his father's auto shop. He had studied at the Feculdade Teologicia Baptista de Sao Paulo, a seminary run by the Baptist convention under American directorship.

Joao considers himself a follower in the tradition of St. Paul. According to the New Testament, St. Paul did not wish to be a financial burden to the people among whom he was spreading the gospel, so he worked as a tentmaker to earn his living. Joao does not accept money for doing God's work, only when he works for his brothers.

Joao said he fervently believes that bringing people the gospel will change their lives. He was inspired to create Telesperanca, a recorded scripture reading and expository statement in Portuguese. It can be heard by dialing 949-5216. He changes the message regularly, adding to his already heavy workload at the shop and at the church.

"I believe God has called me to his work. When God calls someone, he must go where God calls him. Some are called to work among the Indians, some are killed for their faith. I was called to work at 14th and P."

He said he does not feel uncomfortable at that location and, in fact, finds that it gives him a chance to talk to people he might not otherwise meet.

Seizing an opportunity recently to speak with one of the women who strut the sidewalks near the shop, and looking to make a conversion, Joao asked her if she practices a religion.

"Of course! I am a Baptist," she shot back, to Joao's laughter.

His three brothers also like the location but for other reasons. George winks and says he likes the scenery, adding, "It's like Ocean City in the summer." Paul, more concerned with business matters, emphasizes the security of the well-policed corridor. "We've never had any problem. There's always a lot of police going by."

As different as they are, the common denominator of the Petrovitch brothers is their optimistic outlook and fondness for laughter. Whether they are talking about God, their homes in the country or the sad state of a customer's car, others around them are likely to end up laughing, too.