The director Peter Sellars believes that Bach wrote his “St. Matthew Passion” not as a concert work or theater piece but as a “transformative ritual reaching across time and space.” That’s the way he presented it in a revelatory performance with Simon Rattle and the Berlin Philharmonic at the Park Avenue Armory in 2014. The orchestra and chorus, each divided into two groups, as Bach stipulated, here became like combating forces in a searing story of faith and doubt, trust and betrayal, community and mob chaos.

Of course, the “St. Matthew Passion,” which tells of Christ’s last days on earth, is a church piece, a sacred oratorio. But how would Bach have presented it at the church where he worked in Leipzig? An affecting answer was suggested on Thursday at St. Peter’s Episcopal Church in Chelsea when Tenet Vocal Artists and the early-music ensemble the Sebastians, who have a string of remarkable collaborations to their credit, performed this masterpiece. It’s likely, many scholars believe, that under Bach the choruses would have been performed with one singer per part. These singers would have also shared the solo arias and even taken the crucial roles of the Evangelist and Jesus.

In its intimacy and directness, this beautifully small-scale performance by Tenet and the Sebastians was just as shattering as the Berlin Philharmonic’s near-operatic approach. In the somber, steady opening piece, the choristers of one group beseech the daughters of Zion to join the lament. “Behold!” they sing. “Whom?, the others ask. The “Bridegroom!” the first group explains. Here, the music was performed by just eight singers, four in each chorus, standing in front of the pews, one group to the left, the other to the right.

In other performances of the passion, you can be swept along by the choral majesty of Bach’s music. In this one, you heard the individual lines — and the individual qualities of the voices — with striking clarity. So, the desperate pleas and the confused responses came through like personal utterances.

It was almost uncomfortable to watch as these singers took small roles one moment then sang an aria the next, as when the strong bass Sumner Thompson transformed from Judas, betraying Jesus with a kiss, into a penitent singing a sublime aria asking to have his Jesus back. The other bass, Charles Wesley Evans, brought tenderness to an aria affirming that it will be easier to take on the cross in his life because Jesus had first done so. Yet, before long, Mr. Evans became Peter, the frightened disciple who denied Jesus three times.

The radiant-voiced Jolle Greenleaf, the artistic director of Tenet, shared soprano arias with the elegant Laura Heimes. The countertenor Doug Dodson and the mezzo-soprano Virginia Warnken Kelsey shared the alto arias. Jason McStoots and Gene Stenger were the impressive tenors.

Tyler Duncan’s naturally burly baritone made him an almost fearsome Jesus. So it was wrenching when this Jesus showed poignant vulnerability in accepting his fate. As the Evangelist, the tenor Aaron Sheehan balanced grace and urgency in relating this oft-told story.

The Sebastians ensemble (Jeffrey Grossman, music director) gave a performance of uncommon naturalness and transparency. Mr. Grossman, much as Bach would have, played the organ continuo part while offering just occasional cues.