But this is [our] opinion, that the power of the Keys, or the power of the bishops, according to the Gospel, is a power or commandment of God, to preach the Gospel, to remit and retain sins, and to administer Sacraments…

This power is exercised only by teaching or preaching the Gospel and administering the Sacraments, according to their calling either to many or to individuals. For thereby are granted, not bodily, but eternal things, as eternal righteousness, the Holy Ghost, eternal life. These things cannot come but by the ministry of the Word and the Sacraments, as Paul says, Rom. 1:16: The Gospel is the power of God unto salvation to every one that believeth. Therefore, since the power of the Church grants eternal things, and is exercised only by the ministry of the Word, it does not interfere with civil government; no more than the art of singing interferes with civil government. For civil government deals with other things than does the Gospel. The civil rulers defend not minds, but bodies and bodily things against manifest injuries, and restrain men with the sword and bodily punishments in order to preserve civil justice and peace.

Therefore the power of the Church and the civil power must not be confounded. The power of the Church has its own commission to teach the Gospel and to administer the Sacraments. Let it not break into the office of another; let it not transfer the kingdoms of this world; let it not abrogate the laws of civil rulers; let it not abolish lawful obedience; let it not interfere with judgments concerning civil ordinances or contracts; let it not prescribe laws to civil rulers concerning the form of the Commonwealth. As Christ says, John 18:36: My kingdom is not of this world; also Luke 12:14: Who made Me a judge or a divider over you? Paul also says, Phil. 3:20: Our citizenship is in heaven…

-Philip Melanchthon, Augsburg Confession, “Article XXVIII: Of Ecclesiastical Authority“