Mohammad called the earliest group of muslims the best group that will ever live. Yet they went to war and killed each other with all of the rightly guided caliphs being assassinated. That and a major split happened between the ones who followed Ali and those who didn’t. With them killing each other for over a thousand years. Yet Allah said that true believers would be at peace with each other.
Either Mohammad was wrong and the first generation weren’t the best ones (or even muslims based on the standard of peace between believers), or there are no true muslims today as there isn’t a single unified version of Islam despite the Quran claiming to be perfectly clear and a perfect guidance for the believers.
P1. Muhammad is reported to have said the best Muslims ever are his generation and the next (e.g. “The best of my nation is my generation, then those who follow them…” – Bukhari 3673 /Muslim).
P2. The Qur’an describes true believers as united in brotherhood and peace, not mutual hostility and killing (e.g. “The believers are but brothers, so make settlement between your brothers” – 49:10; “Hold fast to the rope of Allah all together and do not be divided” – 3:103).
P3. Historically, that “best” generation split into rival camps, fought bloody civil wars (Camel, Ṣiffīn, etc.), all four “Rightly Guided Caliphs” were assassinated, and a permanent Shia–Sunni split rooted in that first century has led to Muslims killing each other for 1,400+ years.
P4. A community characterized by civil war, assassination, and enduring sectarian division does not match the Qur’anic description of united, peaceful believers.
C. Therefore, either Muhammad was wrong about that generation being the “best believers,” or the Qur’anic description of true believers as united and at peace is not actually borne out in Islam’s real history; in both cases, Islam’s claims about its own community and guidance are falsified.
Accept the Sunni claim: the Sahaba and first generations are the best Muslims and rightly guided.
Then you must also accept that:
Result: Qur’anic promises/descriptions about believers’ unity and brotherhood are empty or false.
Result: Either the transmitters and models of Islam (first generations) are corrupt/unreliable, or the hadith canon and Sunni narrative are wrong—both undercut Islam’s credibility.
So: either the “best” Muslims violate Islam’s own standard for believers, or there have effectively been no clearly true, unified Muslims at all. In either case, the Qur’an + hadith claims about Islam’s community and guidance don’t hold up.