Either 1) the Church was totally depraved or 2) it was not. 1) If the Church was totally depraved then Luther et al. may have been justified in abandoning the Roman Church for it was not the Church of Christ.
Either 1a) the Church of Christ remained upon the earth or 1b) it did not. 1a) If it remained upon the earth, then Luther et al. should have abandoned the Roman Church and been reunited to the true Church of Christ. Luther et al. did not become united to any Church but began their own, under 1a) this is unjustifiable.
If 1b) the Church of Christ no longer remained upon earth, then Satan wiped the Church from the earth, Christ is a liar, and Christianity is a farce. The faith of Luther et. al is unjustified and there is no true Church of Christ. Under 1b) the actions of Luther et al are unjustifiable, since it denies the faith they profess.
If 2) the Church was only partially depraved, then the actions of Luther et al were acts of schism and a break from the true Church of Christ. Luther et al did not reform the Church, but departed from the One Church and the One Shepherd to form another church. In faith, hope and love, Luther et al should have remained in the Church to heal it wounds, curb its depravity and maintain Christian unity. Under 2) the actions of Luther et al were unjustified.
Therefore, the actions of Luther et al were unjustified and represents a day of great sorrow. Either 1a) we remain out of communion with the true Church, 1b) Satan has victory and Christ is a liar, or 2) the Reformation represents a great schism and wound upon the Body of Christ.