Luther's concept of preaching as 'teaching and exhortation' arises out of his concern for 'poor souls' entangled in the systems of the medieval church. His 'fulminations' against three systems (the penitential, monastic, and sacramental) are examined to demonstrate his sensitivity to poor souls caught in them (systemic righteousness); in each instance they could easily be set free by the righteousness that comes graciously by faith. 'Teaching' is therefore an essential task to help people recognize their captivity and the true righteousness offered in Christ. 'Exhortation' is necessary to encourage their movement from that bondage to freedom in the graciousness of God.
Riegert, Eduard R.
"To impart to everyone a little of what God has given me: an aspect of Luther as preacher, Part 1,"
Consensus: Vol. 10
, Article 1.
Available at: http://scholars.wlu.ca/consensus/vol10/iss2/1