Reformation Sunday
Luther nailing his 95 theses to the cathedral door in Wittenberg. (Although Luther wrote and published the 95 theses, most scholars believe he didn't actually nail them to the door.)
On Oct. 31, 1517, a young monk, dissatisifed with some of the practices of the Catholic Church, wrote a letter to his superiors about his problems. With the letter he included 95 propositions for discussion and debate. Although this was not the first time someone had questioned the authority and practice of the Church, Martin Luther's act marks the symbolic beginning of the Reformation, of which most of us are spiritual heirs.
Accordingly, many Protestants--principally Lutherans, but also Presbyterians and other Reformed denominations--celebrate October 31 as Reformation Day. For convenience, local churches often transfer the celebration to the preceding Sunday, hence the name Reformation Sunday.
In earlier days, when there was a great deal more animosity between Catholics and Protestants, the latter group often celebrated Reformation Day as we would celebrate a military victory. There would be triumphal processions, hymns glorifying the church, and often the sermon would be a diatribe against the "Papists." (To be fair, during the period the Catholics--in a different part of Europe--would be dealing the venom right back to the "heretics.")
Today, while the hymns remain (as they should!) many Protestant and Catholic
churches use Reformation Sunday as a opportunity to highlight areas of common
agreement. On Oct 31, 1999, the Lutheran World Federation (of which the
ELCA is a member) and the Roman
Catholic Church signed a joint
declaration on the doctrine of justification, clarifying positions where
Lutherans and Catholics agree and disagree.
Readings and Other Resources
Project Wittenberg has online editions of Luther's works, including the 95 Theses, and works by other Lutherans.
Reformation Day by Rev. J. Thomas Shelley gives some more background on the state of the church in Luther's time and some thoughts on the appointed Scripture readings.
Reformation Sunday from the PCUSA offers a Presbyterian slant on the celebration, including sermon helps and hymn suggestions.
Speaking of those, the readings appointed for Reformation Sunday are:
Jeremiah
31:31-34
Psalm
46
Romans
3:19-28
John
8:31-3