The response is:

The lies and falsehood (1) contained in this statement, and its unjust disparagement of the best members of the Ummah, are too evident to escape notice. This may be demonstrated (2) from several angles.

The first is this:

His statement, “Their opinions varied according to their varying desires,” would mean that all of them followed their desires: that none among them sought the truth or desired the countenance of Allah Most High (3) and the Hereafter, and that none based his position on considered judgment and inference from evidence. The generality of his wording includes Ali and everyone else.

Yet those whom he described in this manner are the very people whom Allah and His Messenger praised. Allah was pleased with them and promised them the best reward, as He Most High says:

“The first and foremost among the Emigrants and the Helpers, and those who followed them in goodness—Allah is pleased with them, and they are pleased with Him. He has prepared for them Gardens beneath which rivers flow, where they will abide forever. That is the supreme triumph.”

[Surah al-Tawbah: 100]

And He Most High says:

“Muhammad is the Messenger of Allah. Those who are with him are firm against the disbelievers and compassionate among themselves. You see them bowing and prostrating, seeking bounty from Allah and His pleasure. Their mark is upon their faces from the trace of prostration. Such is their description in the Torah. Their description in the Gospel is that of a crop which puts forth its shoots, strengthens them, grows thick, and stands firm upon its stalks, delighting the sowers, so that through them He may enrage the disbelievers. Allah has promised forgiveness and a tremendous reward to those among them who believe and perform righteous deeds.”

[Surah al-Fath: 29]

And He Most High says:

“Indeed, those who believed, emigrated, and strove with their wealth and their lives in the cause of Allah, and those who gave them refuge and support—they are allies of one another.”

Up to His words:

“Those are truly the believers. For them are forgiveness and an honorable provision—and those who later believed, emigrated, and strove alongside you are among you.”