SANTA ROSA, Brazil (AP) — At dusk in this small indigenous village, Antelmo Pereira calls local Catholics to prayer, changes into a white robe and leads a religious service that is the closest thing the faithful in this remote part of the Amazon can get to a proper Mass.

Speaking in the indigenous Ticuna language, he leads a recital of the Lord’s Prayer, reads a passage from the Gospel of Matthew and delivers a sermon on accepting Jesus into one’s heart, as cicadas chirp loudly in the jungle that lies just beyond the recently built Catholic church.

Pereira, 61, has been a part-time missionary...