Happy Reformation Day, everyone!
My friend Sam and I made this video for Bethel’s Christianity and Western Culture class several years ago. (The words are by a Lutheran pastor from Iowa.) Remarkably, it’s now been seen well over 120,000 times on YouTube, and it never fails that we run into or hear from excited students who have already seen it in a Confirmation or AP History course.
We’ve also seen plenty of less flattering comments on YouTube from Catholics who, rightly, don’t view this as a perfectly wonderful day in the history of the Church. While I think most Roman Catholic clergy and many laity would agree with a good part of Luther’s critique, I grieve with them that the Reformation caused a fracturing in the Body of Christ.
I’m a Protestant, but there are days (sometimes even this one) when I suspect that Erasmus was right:
Some things Luther sees as wrong. But when he tears away at them he does more harm than good. No matter how hard you try humans will always make mistakes; some cures are worse than
the disease. (from a 1524 letter to Philipp Melanchthon)
The Pietist Schoolman 
Unity in error is not Christian unity, it is rebellion against the truth. The Reformation simply was God’s instrument to bring back the light of Scripture to the people, so that they could judge for themselves and flee from the corruptions of Rome. As has been well said:
“Unity in error is not Christian Unity; but by imposing the necessity of erring as a term of Union, Rome became guilty of a breach of Unity, and so the sin of schism lies at her door.” Bp. Christopher Wordsworth; 1866; Union with Rome: “Is not the church of Rome the Babylon of the Apocalypse?”.