RECIFE, Brazil – Sweat dripping down his back, Rinaldo de Lima Andrade took a seat in a metal chair facing the Torah.

“I am the descendant of Jews,” Mr. Andrade, a black man who wears a deep blue yarmulke, said conclusively in Portuguese as he settled in for a prayer class. He was born Catholic and later became an evangelical Christian.

But after a stunning discovery revealed this sweltering port city’s Jewish past five years ago, Mr. Andrade joined scores in Recife suddenly claiming Jewish ancestry. “I believe it comes from my mother’s side,” he says.

When archeologists uncovered the oldest synagogue in the Americas deep under the heart of Old Recife’s Street of Benevolent Jesus, it set off a Jewish renaissance of sorts in Recife, a booming city in Brazil with about 1.5 million inhabitants.

“It’s strange because Israel is so unpopular, and yet people are interested in becoming Jewish here,” the director of Recife’s Jewish school, Marcelo Kozmhinsky, said. “People call and say, ‘I know I’m a Marrano.’ They say they cook differently, light candles, have a special process of burying, they clean house on Friday. Everyone has some connection.”

Mr. Kozmhinsky and administrators of Recife’s other Jewish institutions receive a constant flood of inquiries requesting guidance investigating Jewish ancestry and Stars of David, which are often paired with crosses or the Virgin Mary, and are worn by people of all faiths.

Sitting in a plush wooden chair inscribed with the insignia of the currently defunct Jewish club in the city, the Israeli Club of Central Pernambuco, Mr. Kozmhinsky said the surge in interest has created a challenge. Some in the highly secular Jewish community of about 1,400 – mostly descendants of Eastern European Jews who arrived toward the beginning of the 20th century – see the newcomers as an exciting addition. But others in the rather insular and affluent community are concerned about the motives of those claiming Jewish heritage.

The most difficult question, to which Mr. Kozmhinsky has no answer, is how to prove claims to a Jewish lineage that has been hidden for centuries. “It’s hard because we are not an authority on these issues,” he says.

Interest in the religion surged last year, when New York celebrated the 350th anniversary of the founding of its first Jewish settlement by a group of 23 Dutch Jews from Recife, who survived misadventures with Spanish pirates and a daring French rescue to create Shearith Israel, a congregation that still survives today at 70th Street and Central Park West.

A flush of press reports documented the celebrations in New York. When Globo, the national TV giant piped into almost every Brazilian home, dispatched reporters to the Netherlands, Recife, and New York to retrace the fantastic journey, Recife’s residents watched with pride.

Most here have been content to just learn about Recife’s Jewish past, but there is also a growing faction of people like Mr. Andrade who are reclaiming what they believe to be their long-lost Jewish heritage and studying the faith.

The director of the Jewish Historical Archive of Pernambuco, Tania Kaufman, says that most people in the state of Pernambuco, of which Recife is the capital, have a Jewish ancestor. Some trace their lineage to immigrants who arrived in Brazil who converted to Catholicism during the Spanish and Portuguese inquisitions in the 15th and 16th centuries. The new Christians settled the region’s lucrative sugar and tobacco plantations. Others say they are descendants of Marranos or crypto-Jews – Jews of Iberian origin who professed to be Christians but continued to secretly practice their faith – and now want to openly practice.

In Recife, according to Ms. Kaufman, few people still practicing crypto-Jewish rituals have been found.

But the lack of proven practitioners hasn’t stopped city residents from deluging the archives with requests to uncover their Jewish lineage.

Ms. Kaufman attributes the trend to a current interest in all things Jewish, probably spurred in part by a trend toward experimenting in alternate forms of spirituality and the decrease of prejudice against the religion that has come with greater exposure.

Judaism is also now seen by many as a way to get closer to Jesus. Once an overwhelmingly Catholic country, Brazil has seen a rapid spread of evangelical Christianity in recent years. As one Anglican priest who recently uncovered his Iberian Jewish heritage , and now observes the Jewish Sabbath, said, “Many Christians observe the Sabbath, just as Yeshua did, the messiah of Israel. Spiritually they are Jews. And some have Jewish blood.”

The city has been without a rabbi for much of its history, and for eight decades the Jewish community in Recife has looked most often to its school, the Colegio Israelita Moyses Chvarts, as the center of Jewish life.

Mr. Kozmhinsky said he requested a rabbi at an annual meeting of Reform Jewish congregations in Sao Paulo last year, mainly to attend to the community’s needs for funerals, bar mitzvahs, and weddings. Months later, he was surprised when he learned a Jerusalem based group, Lost Jews, which helps individuals interested in Judaism convert to the faith, was planning to dispatch a rabbi to Recife.

While Mr. Kozmhinsky, who shares his windowless office with the new rabbi, was concerned the Lost Jews mission comes too close to proselytizing for the highly secular community, he is grateful for a religious authority to provide a Jewish response to the many claiming Jewish ancestry.

“I think he is welcome at this moment because he can try and resolve this problem,” Mr. Kozmhinsky said.

The privately financed group knows its subject well. They have already scoured remote areas around the globe for Andean tribes and Chinese peasants who are not considered Jewish by Jewish law, but maintain they have a connection with the Jewish people.

According to the director of Lost Jews, Michael Freund, Brazil has the largest concentration of crypto-Jews in the world.

“You’ve got to get to Brazil,” said Mr. Freund, speaking from Jerusalem in a telephone interview. “Because that’s where in terms of numbers the potential is enormous.”

The Inquisition was late to reach Brazil, arriving at the end of the 16th century, and among the country’s early settlers were many crypto-Jews and new Christians who came in search of religious freedom, as well as economic opportunities. In the early 1600s, a reprieve came with the Dutch occupation of northeastern Brazil. For three decades, Recife, the only open Jewish settlement during colonial times, flourished both religiously and economically, with its members serving as middlemen, traders, and plantation owners. At 600 families, Recife’s Jewish community had two schools, a cemetery, and the first synagogue in the Americas, Kahal Zur Israel, or Congregation Rock of Israel.

But when the Portuguese regained control of northeastern Brazil in 1654, the Dutch were given three months to depart. Most of the ships left for the Netherlands and the Dutch Antilles, with one group running astray and ending up in the settlement of New Amsterdam, or what is today New York.

Despite the Portuguese ultimatum, however, as much as half of the Jewish community remained in Brazil. Space on the ships was limited, Ms. Kaufman said. Those who stayed behind were forced to convert or hide.

The Inquisition’s leaders did their best to bury all traces of Jewish influence, renaming what had been the Street of the Jews the Street of Benevolent Jesus. Still, well into the 18th century, reports continued to reach Lisbon’s office of the Inquisition of clandestine Jewish observances.

Until the arrival of the Lost Jews rabbi, for the past decade or so, the man with the most knowledge of Judaism in Recife, Isaac Essoudry, has been the self-professed “guide and educator of the Marranos, helping them so they can return to Judaism.” Born to Moroccan immigrants in Belem, a city at the mouth of the Amazon, Mr. Essoudry lived in Israel for many years and has received more instruction on Judaism than almost anyone in Recife.

In the 1990s, his group took over the one synagogue in Recife, in a neighborhood that once housed the Jewish community but is rapidly deteriorating. They still go there Saturday mornings, but on Friday nights the streets are too dangerous, he said, and they instead congregate in Boa Vista, a middle-class neighborhood where the 70-year-old Mr. Essoudry welcomes up to a dozen students for lessons in Judaism.

While some question the motives of those who claim Jewish heritage, the bearded Mr. Essoudry welcomes them. “Everyone who wants to come, I accept them,” he says.

Mr. Andrade rushed in late to his prayer class on a recent Friday night and took his seat in the semicircle of metal chairs.

Still unable to authenticate his hunch that he has Jewish ancestors, Mr. Andrade said he plans to investigate. Either way, he wants to convert to Judaism, go to Israel, and send his daughter to the Colegio Israelita.

“I am going to stay Jewish, without a doubt,” Mr. Andrade said as he prepared to pray. “For me, Judaism is the only true faith on Earth.”