In Judaism, the meaning of the word “brother ” sometimes extended beyond those who were literally relatives, but its meaning was still restricted to those within the Jewish nation and did not include Gentiles.
أَمَّا « ٱلْأَخُ » فِي نَظَرِ ٱلْمَسِيحِيِّينَ فَهُوَ أَيُّ مَسِيحِيٍّ حَقِيقِيٍّ بِغَضِّ ٱلنَّظَرِ عَنْ قَوْمِيَّتِهِ .‏