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.
“Christ alone.” Christ is the sole mediator between God and humanity; salvation comes through him alone, not through saints, priests, or any other intermediary.
In Doctrine — What Lutherans teach, and where it differs from neighbouring traditions.