Nadwi wrote the book that reframes this entire argument, and he wrote it at thirty-three.
Its title is a question disguised as a statement: What the World Lost by the Decline of the Muslims.
Sit with the construction, because everything is in it. Not what the Muslims lost. Not what was done to them. What the world lost.
An argument that runs "our civilisation was great, then it was attacked, and it should be great again" is a grievance with a flag on it. It is emotionally available, it is partly true, and it commits you to nothing except resentment.
Nadwi's version cannot be read that way. If the loss was humanity's, then restoration is not a Muslim interest to be pursued against everyone else's. It is an obligation owed outward, and the people who dropped the trust are the ones being indicted.
His premise is that Islam was not given to the Muslims for themselves. It was given through them, as a trust, for everyone. Which means the decline was not a defeat suffered. It was a duty abandoned, and the Muslims are the defendants in his account, not the plaintiffs.
When Islamic civilisation stopped functioning as a moral force in the world, the trust was not passed to anybody else. It was simply left unfulfilled.
Nadwi's argument is that what took over was not a rival moral framework but the absence of one. Europe did not replace divine justice with a competing account of divine justice. It replaced it with power, profit and national interest, and then built institutions to administer those efficiently.
The objection is real and Nadwi would have known it.
It is convenient for a Muslim scholar to conclude that the world needs Muslims. Every tradition believes its own absence is humanity's loss, and the argument has exactly the shape you would expect from someone who wanted that conclusion.
Two things make it worth more than that.
The first is that it is an indictment before it is a boast. If the trust was given and dropped, the negligence is Muslim negligence. Nadwi spends most of the book on what the Ummah failed to do, not on what was done to it, and a self-serving argument does not usually allocate blame that way.
The second is that it is falsifiable, at least in principle. It predicts that a world without a civilisation oriented to divine justice would produce specific outcomes: extraction without limit, violence without account, technical capability outrunning moral capacity. Those are checkable, and the last five centuries are the data.
You can dispute the causation. You cannot dispute that the predicted pattern is what happened.
The verse he builds on is usually quoted as flattery. You are the best nation produced for mankind. The flattering half is the first four words, and it is the only half most people quote.
The operative half is the last two. Produced for mankind. Not superior to it. Produced for it, the way a tool is produced for a purpose, and a tool that has stopped doing the thing it was made for has no standing to be proud of what it is.