Recently, for reasons that do not concern anyone outside my local church, I preached a sermon on Discipleship and Discipline. It was part of a series on 2 Corinthians and I had been assigned 2 Cor. 2:5 - 11. On these few verses I hung an overview of the disciplines that Paul would have taught the Corinthians plus what God reveals elsewhere e.g. Revelation.
It is serious stuff and is not to be preached lightly. God always makes sure that if a sermon is not part of a preacher's experience, it soon will be! Budding preachers take note!
God is returning discipline and discipleship to His True Church because He would have her a pure and spotless Bride. Those who resist these things declare their true allegiance, unless they should repent and seek His forgiveness - but it is all about forgiveness. God is merciful.