But he ended up in mutiny instead, mostly because he called the pope "the Antichrist" in 1518 (obviously he was not in communion with the Pope at that point!) and was declared excommunicated in 1520 --- not so much a decree as a declaration of what had long been a fact.
Not that I want to re-argue the whole history of the wrongly-called Reformation, which was rather, a rebellion. Just like, if you leave your wife, that's not reconciliation, that's divorce.
The larger point is, all those who left the Church ended up claiming that the Church was apostate,though they don't all agree on when the Church went apostate. Some claim it happened before the death of Peter and Paul! They all agree ---- as far as I know --- that at some point, the Church failed.
Just Petered out, I guess.
Not so.
Luther never claimed, nor did the reformers, that 100% of the church apostatized.
The Scriptures never claim a 100% apostasy would take place. Jesus did ask at one point if -- when He returned -- would He find faith on the earth? (Luke 18:8)
Actually, a prophesy by the apostle Paul shows that God would be glorified in His church throughout all ages -- unto the end:
20 Now to him who is able to do immeasurably more than all we ask or imagine, according to his power that is at work within us, 21 to him be glory in the church and in Christ Jesus throughout all generations, for ever and ever! Amen. (Eph. 3:20-21)
So even when unfaithful popes and other church leaders popped up (or should I say "poped up"?), God remained faithful and a remnant of the faithful remained on the scene.
To claim that the Roman Catholic church didn't need ongoing reformation through the centuries would prompt a need to duck history altogether.
It would be tantamount to claiming that the Israelites never needed reform...and such a person claiming that would entirely flunk the Old Testament...with HUNDREDS of OT verses (probably a few thousand, actually) devoted by God to accomplishing such needed reform!