On: every psalm and song in the daily prayers uses today’s English. Off: all of them use the older “thee and thou”. Until you choose, the Songs of Zechariah, Mary and Simeon use today’s English, as most churches sing them. The Lord’s Prayer and the prayers for the dying show the form most people learned.
The 1521 imperial assembly where Luther refused to recant. The words most associated with it — “Here I stand, I can do no other” — may be a later addition; the refusal itself is documented.
In History — The Reformation, and the people who carried it.