The answer is Chorale
Singing specific Chorale with a congregation as been a critical part of Lutheran religious services since centuries.
<span>Lutheranism itself is a major branch of the Protestant belief and is named after the leader of the movement, the German reformist Martin Luther.</span>
The movement started in 1517 and is today a major branch of Christianity.
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It's called spontaneous recovery
Schizophrenia is I think what fills the blank in the sentence.