because sharing the same homeland is, in itself, a distinguishing trait that sets them apart from the land in which they feel like strangers.
Indeed, if two men meet while travelling or in a foreign country and happen to resemble each other in their turban, clothing, hairstyle, mount, or the like, they will feel a greater sense of harmony than they would with anyone else.
You also see people engaged in the same worldly trade bonding with one another in a way they do not bond with outsiders—sometimes even while they are otherwise enemies at war, whether over power or over religion. Likewise, kings and similar leaders—despite the distance between their realms—share a certain affinity that breeds resemblance and mutual consideration. All this is dictated by human nature, unless religion or a particular motive prevents it.
So if resemblance in worldly matters engenders affection and loyalty, how much more will resemblance in religious matters do so? Such resemblance leads to an even stronger kind of allegiance, yet love and loyalty toward them are incompatible with faith… Allah, exalted is He, says: “You will not find a people who believe in Allah and the Last Day loving those who oppose Allah and His Messenger—even if they were their fathers, their sons, their brothers, or their tribe. Such are the ones in whose hearts He has inscribed faith and whom He has strengthened with a Spirit from Himself” (al-Mujādilah 58:22).
He has therefore declared that no believer loves a disbeliever; whoever shows affection to the disbelievers is not a believer. Outward resemblance is a likely cause of such affection, and thus it is forbidden.”
He said elsewhere (pp. 6–7): “These inward and outward matters are interconnected and correspond to one another, for whatever feeling or state establishes itself in the heart produces outward actions, and whatever manifests outwardly of the various…"