The Al Firdaus Ensemble, from Granada, Spain, perform at the Diyanet Center of America in Lanham, Md., Saturday. From left are Abdessalam Naiti, Salma Vives, Ali Keeler, Omar Benlamlih and Muhammad Domínguez. (David Montgomery/The Washington Post)

At about the same time that Donald Trump was reminding everyone at the New Hampshire Republican presidential candidates’ debate Saturday evening that he had called for a ban on Muslims entering the country, a violin player and singer of Islamic religious songs named Ali Keeler was about to perform at a Turkish mosque in Lanham, Md., just outside the Capital Beltway.

Keeler, born in London and now based in Granada, Spain, is as surprised as anyone that his band of devout troubadours called the Al Firdaus Ensemble is filling concert halls in the United States. Given all the controversy over Islam in this country, “we didn’t know what to expect,” he said.

Keeler had wondered if there would be problems getting into the country. If there would be an American audience for a quintet of virtuosos playing songs in a style that is hundreds of years old. Then there was all the political rhetoric. Keeler was well aware that if the person in the White House a year from now is President Trump, a tour like this featuring Muslim artists from abroad might be impossible.

[Thumbs down from the world on Trump’s proposed ban on Muslims]

But Keeler has faith.

“I think, really, exactly what is going on in the end is going to be very positive for Muslims,” he said with the serene confidence of a man whose lyrics are rooted in mystical Islamic poetry and texts in which amazing marvels do come to pass, if you just believe. “I’m confident that the majority of Americans actually are in favor of a pluralistic, diverse society.”

The remarkably timely tour of Al Firdaus has grown organically, as word spread among networks of young professional Muslims engaged in building vital social, educational and religious scenes in cities across America. The ensemble — which takes its name from the most elevated part of Paradise — played before several hundred people in the Princeton University Chapel on Friday night. Before that, the group performed in a chapel in Chicago. It is eventually headed to the San Francisco Bay area.

Two dates this weekend in the Washington area were added when Ali Elashram, 25, who works in information technology and knows Keeler, learned that Al Firdaus would be on the East Coast. He connected with Pervaiz Bhatti, a member of the Yaro Collective, a Washington-based network devoted to nurturing the Muslim community and deepening the understanding of Islam. The collective is named after Mahmoud Yaro, an African slave who gained his freedom, went into business and died in 1823 in Georgetown, where his devotion to Islam was well known. (Also referred to as Muhammad Yaro and Yarrow Mamout, his portrait was painted by Charles Willson Peale.)

[Who was Yarrow Mamout, one of America’s earliest celebrated Muslims?]

Word of Al Firdaus spread over Facebook, and performances at the Turkish Diaynet Center of America on Saturday and the GALA Hispanic Theatre in Columbia Heights on Sunday quickly sold out, a total of nearly 450 seats.

For those filling the halls, it was more than a night out.

“There’s been an assault on what Islam is and was,” Elashram said. “This is a way to reconnect to that heritage. . . . Islam is a way of life.”

While the musicians of Al Firdaus did not set out to influence the contentious discussions around Islam, they are aware that this tour, at this time, in some small way could have an impact. Their music is far from political. It’s all about beauty and faith and peace and devotion — which is a point in itself. Inherent in this musical tradition is the idea that truth is beauty and beauty is truth. Thus, for an artist to create or convey an Islamic thing of beauty is to tell a truth about Islam.

“When Islam has such bad press, we are ambassadors,” said Muhammad Domínguez, who plays the darbuka, a hand-held drum, in the ensemble. “I think there is no better moment for us as Muslims and believers and followers of the prophet Muhammad to bring these events to the whole world. Once falsehood appears, you should confront it with the truth. Al Firdaus is an open window to show the people the beauty of Islam.”

The Saturday and Sunday concerts were billed as “Sounds of the Alhambra,” referring to the ancient Moorish palace and fortress in Granada that still stands as a tranquil, if crowded, tourist attraction. Most of the people in the audience Saturday were connected to the Muslim community. They ranged in age from babies to seniors, and some dressed in traditional headscarves or robes.

With violin, cello, two darbukas, a harp-like qanun and sinuous vocals, the musicians of Al Firdaus held the audience silently spellbound at some moments and inspired them to ebullient poly-rhythmic clapping and singing at others. The melodies explored the common harmonic river fed by musical tributaries of Arabic, Moorish, Turkish, Celtic, flamenco and Andalusian sources. The words, mostly in Arabic, were composed epochs ago by holy men and mystical poets.

The last line in an extended, exuberant Celtic-style jam touched on Islam’s traditional acknowledgement and respect for other faiths. Keeler translated it from the Arabic:

Muhammad is the messenger from God
Moses is the one that God spoke to
And Jesus is from the spirit of God
Upon them be blessings and peace

A highlight was a piece called “Madha Morisco,” which the musicians composed with a traditional melody to accompany words from a 17th-century religious manuscript discovered above a false ceiling when a house in an Adalusian village was being restored in the 1880s. It was written in the language of persecuted Spanish Muslims, the Moriscos, an old form of Spanish transliterated into Arabic.

A facsimile of the manuscript was projected behind the musicians. Keeler stood and, using his violin bow like a professor’s pointer, led the audience through a translation of the Spanish-Arabic words into English:

Your word will come forth
Your prayer will be heard
Embrace the greeting of peace that I offer
These are the deeds of Muhammad

To open the program Saturday, a poet from the San Francisco area named Baraka Blue delivered some of his works, composed in English but reflecting Islamic themes inspired by the faith’s mystical poets, with the subtlest touch of hip-hop swagger.

Between two sets by Al Firdaus, David Dakake presented his songs in a hybrid style that he calls “American Islamic folk music.” Strumming minor chords on a steel-string guitar, Dakake sings lyrics in English that narrate dramas in the life of Muhammad, weave together key insights and sayings of Islam, or speak in the voices of earnest seekers of the faith.

Dakake, an adjunct professor of religious studies at George Mason University, says that as Islam has moved through the world, its practitioners have always refashioned the artistic traditions of other lands to reflect the faith in new idioms. That will increasingly be the story of American Islam, he predicted. And it’s not unlike the music of Al Firdaus, weaving the sounds of East and West, just when the seams look in danger of being torn apart.