How do we reconcile the noble verse "The believers are nothing but brothers" which implies limiting brotherhood to Muslims, with Allah's saying about His prophets, "And to 'Ad [We sent] their brother Hud" and "And to Thamud [We sent] their brother Salih," where brotherhood was affirmed for disbelievers?

The true brotherhood that necessitates loyalty and love is the brotherhood of faith and religion, exclusively among Muslims, as Allah Almighty says: (Indeed, the believers are brothers), and as the Prophet, peace and blessings be upon him, said: (A Muslim is the brother of a Muslim). As for a disbeliever, he is not a brother to a Muslim in this regard, and it is forbidden to take him as a guardian or a friend.

It is permissible to affirm brotherhood based on lineage or shared humanity between a Muslim and a disbeliever, such as in the words of Allah Almighty: (And to 'Ad, their brother Hud). However, one should avoid using the term "brotherhood of lineage" if it might imply sharing in their falsehood or loving them, in order to safeguard the religion and preserve the creed. This is why it was not said, "their brother Shu'ayb" concerning the people of Al-Aykah, because they worshipped a tree.