Utopia- Meaning: A place of ideal perfection especially in laws, government, and social conditions. It's an ideal place or state.
As they were praying they realized that church was their Utopia. They discovered that church and their religion was what made them happy.
This means that church was their ideal place to be. Utopia is a place of ideal perfection which is what they were thinking while they were praying and while they were at church. Utopia can be many different things for others but for them it was church.