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 1529 meeting between Luther and Zwingli that agreed on fourteen articles and failed on the fifteenth, the Lord's Supper. The point at which the Reformation divided into Lutheran and Reformed.
In History — The Reformation, and the people who carried it.