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.
What Christ's death accomplishes. Lutherans have used several images without making any one of them official doctrine: substitution, victory over the powers, and reconciliation among them.
In Doctrine — What Lutherans teach, and where it differs from neighbouring traditions.