The theft at Sts. Peter and Paul Church occurred last week, police said. Investigators said the thieves may have begun stripping copper from the roof Thursday night and returned Friday. They made off with about $6,000 worth of scrap metal.
Church officials discovered later the book of gospels had vanished. There was evidence the thieves got into the church through a basement window.
The Rev. Volodymyr Zablotskyy said the book has been at the church at least since 1933, the year the current building opened. The parish was founded by immigrants from Eastern Europe in 1894.
"It's a connection to our founders," he said. "In many ways, it's a reminder that even during times of struggle, great things can be accomplished when communities pull together."
Investigators said there was another attempted break-in at the church Sunday night.