“Muslims cannot even agree with each other. There are dozens of sects, each saying the others are wrong. How can any of it be true?”

The frustration behind this is usually real and rarely abstract. Someone was told their practice was wrong, or watched two people who both claimed the religion insist the other had left it.

But look at what the argument assumes: that a true religion would produce uniform agreement among its adherents. Nobody ever promised that, and the Prophet in fact predicted the opposite — that the community would divide into many groups. The number reported, seventy-three, is an idiom for multiplicity rather than a headcount, in the way "a thousand" works in older speech. A religion whose founder said the community would fracture is not refuted by the fracture.

Most of what gets counted as division is jurisprudence: differences over how rulings are derived. Four Sunni legal schools have coexisted for more than a thousand years, each treating the others as valid, and a Muslim may follow any of them. That is a method for holding disagreement, built deliberately, and it is the opposite of collapse.

Then test the argument itself. Christianity has thousands of denominations. Judaism, Buddhism, and every school of philosophy have split comparably. If internal disagreement falsifies a position, then nothing anyone has ever believed survives, and the objection takes itself down with everything else.

People disagreeing about a thing is evidence about people. It is not evidence about the thing. The men shouting at each other are not the religion, and you were never required to take them as its representatives.