Minecraft Dungeons:Church

The church is a building accessible after the hero completes for the first time. It is reachable via a path to the left of where the hero finds the broken nether portal. Once the hero reaches the church for the first time, a drawbridge is able to be lowered to make reaching the church easier. The church allows the hero to unlock the runes, allowing access to the secret mission Mooshroom Island and two obsidian chests.

Inside the church are several developer portraits found in the credits for the game. In the end, there is a dog portrait. Clicking on the dog reveals a hint toward the location of an undiscovered rune.

Inside
The inside appears that of a normal church. There is a big red carpet in the middle of the room that goes all the way from the entrance to the dog painting. And the end of the carpet is a grass block block image. The sides are lined with rows of seats, along with many, many pictures of the developers as seen in the credits on the wall. There are also banners hanging down from the sides of the room. At the end of the inside of the church is the button that lets the player see collected runes.

Unlocking ???
Upon completion of Obsidian Pinnacle, and then activating the button in the back of the church, several secret areas appear where nine must be collected. A painting inside the church gives hints on how to unlock them.

The levers/buttons that open the rooms containing runes generate only after visiting the church, which requires defeating the Arch-Illager on default mode.

After the hero collects the nine runes and returns to the church, the golden button with a cow face unlocks a room with two obsidian chests and a map, which reveals the secret mission. On the level selection map, this can be found behind the in the northwest corner of the map.

Trivia

 * The runes required to unlock the Mooshroom Island spell out the words "BOVINE PATH", as can be seen in datamined files.