I have been meditating on this since Sunday afternoon: Do I go with the readings for Proper 25 or for Reformation Day this Sunday (sincer there will be no service on Friday)? Next year is a whole other situation with Reformation Day falling on a Saturday and the likelihood of an afternoon worship service!
The readings for Proper 25 continue the theme from the last couple of Sundays, namely, Jesus' increasing Anfechtung (spiritual attack) at the hands of the chief priests and the Pharisees as they seek to question Him so as to find a legal reason to arrest Him and kill Him.
The readings for Reformation summarize some of the key themes of the movement, namely, that we are justified by faith in Christ and not by doing the works of the law.
Either way, this Sunday will be a celebration of the Reformation at church. I am leaning toward using the readings for Proper 25 to keep the lectionary continuity going as the church year draws to a close. The Matthew 22.34-46 reading has some good themes that can easily be tied into the work of the Reformation.