Fourth, God’s people or holy Christians are recognized by the office of the keys exercised publicly. That is, as Christ decrees in Matthew 18 [:15–20], if a Christian sins, he should be reproved; and if he does not mend his ways, he should be bound in his sin and cast out. If he does mend his ways, he should be absolved. That is the office of the keys. Now the use of the keys is twofold, public and private. There are some people with consciences so tender and despairing that even if they have not been publicly condemned, they cannot find comfort until they have been individually absolved by the pastor. On the other hand, there are also some who are so obdurate that they neither recant in their heart and want their sins forgiven individually by the pastor, nor desist from their sins. Therefore the keys must be used differently, publicly and privately. Now where you see sins forgiven or reproved in some persons, be it publicly or privately, you may know that God’s people are there. If God’s people are not there, the keys are not there either; and if the keys are not present for Christ, God’s people are not present. Christ bequeathed them as a public sign and a holy possession, whereby the Holy Spirit again sanctifies the fallen sinners redeemed by Christ’s death, and whereby the Christians confess that they are a holy people in this world under Christ. And those who refuse to be converted or sanctified again shall be cast out from this holy people, that is, bound and excluded by means of the keys, as happened to the unrepentant Antinomians. (Luther’s Works, v.41, p.153)
Picture: Beehive, A symbol of the unity of the communion of saints.