Penance after grave sin - a Protestant perspective (Martin Bucer, 1500s)

What should you do if a Christian commits a grave sin and has confessed it? How should their local church respond? 

Martin Bucer (1500s), in his classic work on pastoral care and church discipline, "On the True Care of Souls", addresses this and other situations with advice that is both Biblical and drawing on road-tested wisdom. 

Based on a text in Ezekiel, Bucer assigns believers to one of five categories. The third category is "hurt and wounded sheep" which Bucer describes in the following details "those who remain in the church and the communion of Christ, but fall into open and notorious sins and abuses, such as abandoning their confession of Christ, denying the truth of Christ, and in other ways blaspheming against God, his holy word and all the things of God; disobedience and sin against superiors; any harm done to their neighbours' property, person or honour by word or by deed; all immorality and intemperance." 

In other words, Christians who don't stop coming to church, but who have fallen into grave sin. 

Bucer connects this with the early church practice of public confession and penance, whereby "When any of the Christians had in some way fallen into serious and public sin, through which others were offended, they were not admitted to the fellowship of Christ's table until they had given the church a clear and satisfactory indication on their repentance and reformation."

Bucer goes on, "... we can see that the apostle regarded this excommunication and penance of those who had fallen into more serious sins, even though they had turned from their sins and were sorry for them, as an ordinance of  and command of the Lord, and not to be neglected in any church: otherwise he would not have blamed the Corinthians so seriously and sharply for having neglected it." Excommunication refers particularly to temporary exclusion from the Lord's Table (Holy Communion). 

Likewise Bucer says, "But this true sorrow and commitment to reformation following more serious and grosser sins is not proved by someone just turning away from the sin he has committed and saying, "I am sorry, I won't do it again." 

Bucer addresses head-on the following question, "What need is there, them, of a lot of correction and penance, after the sinner has forsaken his sins, repented and desired grace?" 

Here is his answer, "there is no need for it in order to obtain the forgiveness of God, nor to atone for past sins, which is done only through the blood of Christ. But correction and penance are needed in order that sins should be better recognised and shunned, and the grace of Christ treasured the more preciously, and more diligence used in order that this grace may not be received in vain, and that precautions might be taken to prevent the person immediately falling into the same sin again."

Later he adds, "Penance is not the a satisfaction for past sins, but a medicine against present and future sins, because it is inteded to purge and purify the remaining lusts and sinful desires and thus to protect against future transgressions."

His final summary reads as follows, "All wounded sheep, i.e. those who are Christians and are in Christ's sheep-pen and continue in obedience to the gospel, but fall into conscious sin, are to be given counsel and help so that through true repentance and amendment of life they may again become healthy and well, i.e. return to real, holy Christian life."