“Impressive,” Michael said.
“Wasteful,” Indigo replied.
Though nearly empty at the moment, Michael guessed the cavernous cathedral could easily seat over a thousand. Behind and above them was a balcony area where two hundred more parishioners could share space with the sizeable choir. Indigo pointed these facts out cheerlessly, like a tour guide in a museum of the mundane. [If Indigo indeed pointed out these facts, you might want to drop "Michael guessed." No need to guess something that's been stated.]
“Too many empty seats?” Michael asked.
“On the contrary, the place is filled every Sunday.”
“Shouldn’t you be happy, then? I mean, to reach so many –”
“Many are here, detective, but I wonder about how many we reach. Most seem to enjoy the anonymity afforded by such a large gathering.”
“Anonymity? As if church were someplace they don’t want to be seen?”
“In a way. I think some don’t want to be noticed on the Sundays they are here so they won’t be noticeable by their absence on the Sundays when they’re not.” [they aren't.]
Michael nodded. He had never been much for attending church himself.
“They needn’t worry,” Indigo continued. “Beyond the core group that sits up front and volunteers for every project, I couldn’t name very many names. Do you know how we keep track of our active parishioners, detective?”
[Same paragraph] “Personalized envelopes. We send them out to everyone at the beginning of each month. People come in to worship and drop a pre-printed envelope in the collection plate with whatever they can spare for the week. and We use them [the ones that get dropped in the collection plate] to take attendance. Can you believe that? We count the faithful like box office receipts.”
Well done. I note that the detective guesses incorrectly at what Indigo meant by "Wasteful," but that Indigo doesn't explain what he did mean.