PORTO, Portugal, Oct. 1 (JTA) — The walls of the spacious synagogue are filled with the chanting of the Shalom Aleichem prayer as a small group of worshipers welcomes the Sabbath. The congregation numbers no more than 20 and has no rabbi. But they sing with enthusiasm amid splendor one would expect to find in a Portuguese cathedral: pink marble pillars, high, narrow church windows, golden letters and colorful patterns adorning the holy spaces. The Mekor Haim Synagogue symbolizes the hope for a renaissance of Judaism in Portugal, where some believe millions of people may have Jewish ancestry. "The potential is enormous. Enormous," says the synagogue´s president, Moshe Medina. The synagogue also is home to a historic past. Mekor Haim was built in the 1920s at one of the poshest addresses in this bustling port city by a decorated Portuguese army captain, aided by wealthy Jews from as far away as London, Paris and Shanghai. Arturo Carlos de Barros Basto had dared to embrace openly his Jewish roots more than four centuries after the Inquisition in Portugal. He also persuaded thousands of other "crypto-Jews" — those who continued to practice Judaism in secret — to do the same. But these descendants of hidden Jews disappeared into the woodwork almost as quickly as they surfaced because of a campaign against Barros Basto backed by the Catholic church, historians say. A local priest fabricated charges of homosexual and indecent acts, such as sucking the infants´ blood during circumcisions, and the army court-martialed Barros Basto. That´s why he´s known as "the Portuguese Dreyfus," after the French army officer who was stripped of his rank on fabricated charges a few decades earlier. Barros Basto died a broken man in 1961. But now, after more than a quarter-century of religious freedom and democracy in Portugal, Jewish organizations here, in Israel and in the United States are pressing the government to rehabilitate Barros Basto. The Porto Jewish community — along with Amishav, an Israeli-based organization working with descendants of Jews around the world — hopes such a move will help spark a Jewish revival. "As far as I´m concerned, 4 million Portuguese today have Jewish blood," said Medina, the community´s Israeli-born leader. His calculation is based on Portugal´s religious makeup before 1496, when King Manoel I — under pressure from King Ferdinand and Queen Isabella of Spain — ordered all Jews in the kingdom to become "New Christians." At the time, after a wave of refugees fled the Inquisition in Spain, between one-fifth and one-third of Portugal´s 1 million people were estimated to be Jewish. Today 10 million people live in Portugal. And many of the New Christians who continued to practice Judaism — the crypto-Jews — settled in villages in the remote regions of northern Portugal around Porto. Ethnographers say there are or may be pockets of crypto-Jews in villages in northern Portugal. The difficulty in tracing them comes from an identity confusion that is rooted in a centuries-old strategy designed to throw off inquisitive Christians. "One day they tell you they´re Jewish, the next they say they´re Christian," said Elvira Mea, a history professor at the Universidade do Porto and, along with Tel Aviv-based journalist Inacio Steinhart, a biographer of Barros Basto. For his part, Medina doesn´t want to guess how many crypto-Jews there are or how many might return to Judaism. But his eyes widen as he talks about the "many families, many families" he expects to fill the carved wooden benches of Mekor Haim. Estrela Oliveira and her sons Simao, 12, and Carlos, 13, are among those already attending. "My grandmother always told me that we were Jewish," Oliveira said after the service. "But we had to hide it." A 49-year-old philosophy professor, Oliveira grew up secretly lighting candles on Sabbath. Her Jewish conviction was only strengthened when her parents sent her to a school run by nuns. "When I would ask why the nuns wouldn´t give me an answer. They would just say: ‘If you don´t believe without asking questions, then you don´t have faith,´ " she said. Oliveira´s surname means "olive tree." When Jews converted, many adopted names from nature, a kind of code that allowed them to identify each other. "Pear tree" is the translation of Carlos Pereira´s last name. After leading the service with Moshe Medina´s brother Marcos, Pereira, 76, recalled how his parents resisted the blandishments of the local priest by saying he´d been baptized at the hospital. "But there was a well-known Jew in the neighborhood who was a barber, who also shaved beards and pulled teeth," said the retired engineer. "He was the one who circumcised me." Medina argues that a Jewish renaissance would be a boon for Portugal, a country that still has one of the weakest economies in the European Union. He notes that Portugal went into decline after its most prominent Jews fled and contributed to the blossoming of Holland and England and Portuguese colonies in India and the Americas. "With the Jews, Portugal was a world power," he says. But despite the role Jews played in Portuguese history, Medina says there is widespread ignorance today about Jewish culture. He recalls a university professor who asked before entering the synagogue whether he needed to remove his shoes — mistaking a Muslim ritual for a Jewish one. That ignorance is also a major obstacle for Portuguese of New Christian origin who want to explore their Jewish roots. In recent months, however, the Mekor Haim community has received weekly visits from an Israeli Orthodox rabbi sent by Amishav to do outreach work in northern Portugal among descendants of the crypto-Jews. The president of Amishav, Michael Freund, calls the crypto-Jews by the Hebrew term "anusim," which means "the coerced." He said the outreach effort goes hand in hand with the campaign his organization is spearheading to rehabilitate Barros Basto posthumously. "Our goal in clearing Barros Basto´s name," he said, "is to show the anusim in Portugal that times have changed and now there is a new atmosphere and they can feel safer in coming out of the closet." Amishav´s campaign so far has led to letters to the Portuguese ambassador in Washington from the Orthodox Union, the Conference of Presidents of Major American Jewish Organizations, the Religious Zionists of America, the Jewish War Veterans of America and Rep. Gary Ackerman (D-N.Y.). In Lisbon, a Defense Ministry source said the requests are being studied, and a "positive result" is expected.