One Sunday, “led by curiosity and good company,” which included George Washington, Adams crossed a “Romish” threshold, to attend afternoon mass at St. Mary’s Catholic Church on Fifth Street, an experience so singular that he reflected on it at length both in his journal and in a letter to Abigail. Everything about the service was the antithesis of a lifetime of Sabbaths at Braintree’s plain First Church, where unfettered daylight through clear window glass allowed for no dark or shadowed corners, or suggestion of mystery. For the first time, Adams was confronted with so much that generations of his people had abhorred and rebelled against, and he found himself both distressed and strangely moved. The music, bells, candles, gold, and silver were “so calculated to take in mankind,” that he wondered the Reformation had ever succeeded. He felt pity for “the poor wretches fingering their beads, chanting Latin, not a word of which they understood,” he told Abigail. The dress of the priest was rich with lace—his pulpit was velvet and gold. The altar piece was very rich—little images and crucifixes about—wax candles lighted up. But how shall I describe the picture of our Savior in a frame of marble over the altar at full length upon the Cross, in the agonies, and the blood dropping and streaming from his wounds? Yet Adams stayed through all of the long service. The music and chanting of the assembly continued through the afternoon, “most sweetly and exquisitely,” and he quite approved of the priest’s “good, short, moral essay” on the duty of parents to see to their children’s temporal and spiritual interests. The whole experience, Adams concluded, was “awful and affecting”—the word “awful” then meaning full of awe, or “that which strikes with awe, or fills with reverence.”
I was amazed that despite his tradition, he was open enough to express positive things about the experience. I will comment on his pity for "the poor wretches." I can't speak for the Catholics of 1770s Philadelphia, but I will say that there is evidence of vibrant knowledgeable faith among Catholic laity in many times and places before the liturgy was in the vernacular. Yes, there are also cases of ignorance of the faith, but that's also true in the Protestant world. In general, I think it is good that the Catholic liturgy is now usually done in the vernacular, although I'm glad that the Latin tradition is being preserved.
I can speculate on two related reasons why Adams may have been so affected. The first is the sacramental presence of Christ in the Catholic Mass. Although I believe from what I've read that Adams had a relationship with Christ, Jesus is present in the Eucharist in a way that Adams would not have experienced before. I have heard many testimonies of people walking into a Catholic Church and feeling a divine presence there, and that has been my experience too. The second reason is that there was worship appropriate to the bodily presence of Christ there at the Mass. It would have been more like the heavenly worship described in Revelation 4-6 than the sermon-focused services to which Adams would have been accustomed.
There is no evidence that Adams ever considered conversion. It would have been practically unthinkable in his world. Still, I'm glad to see that he took the time to describe this experience.