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.
God's favour given freely, not earned and not deserved. In Lutheran usage grace is not a substance infused into a person but God's own disposition toward them for Christ's sake.
In Doctrine — What Lutherans teach, and where it differs from neighbouring traditions.