Zwingli wrote, in defense of Luther, in 1520 shortly after Luther had been excommunicated-
As to Luther, the largest part of this evil [i.e., the Roman uproar about his teaching] must be laid at the door of those who have preached and written about indulgences and the power of the Roman Pontiff things which no educated and religious ear could bear, so that as far as the beginning of this disturbance is concerned Luther may fairly seem to have been influenced by devotion and zeal in the cause of the Christian Religion.
Moreover, those who do not excuse his beginning afterwards to write more bitterly, yet make allowance for it, saying that he was not altogether without reason angered by the exceedingly bitter hectoring and taunts of certain persons. Without having yet read his books, they raised among the people the cry of “Heretic, Antichrist, Schismatic,” before the Pope had made any public interposition of his authority in the matter at all. Nobody admonished or confuted him, though he declared himself, as he even now declares himself, ready for discussion with any one—they only damned him.