Ein Tattoo wird durch den Koran nicht verboten. Es wird durch eine Hadith verboten. Für orthodoxe Muslime ist der Grund einfach, weil es dazu einen Hadith gibt. Moderne Erklärungen sind meist, weil es eine Schmerz zufügen am Körper ist. Dazu passt aber nicht, dass dann die männliche Beschneidung geboten wird und die weibliche Genitalverstümmlung von den meisten Gelehrten bisher zumindest geduldet wurde (wenn nicht gar zum Gebot erklärt wurde!). Da die meisten Gelehrten eine sehr konservative Auffassung haben und grundsätzlich alles "Neue" als etwas teuflisches ansehen, ist man sich sehr einig wenn es um Tattoos anbelangt.
1) Abdullah Ibn Masud reported: Allah cursed those women who tattoo and who ask to be tattooed, those who get their hair plucked out and those who make spaces between their teeth for beautification changing what Allah created.
This news reached a woman of the tribe of Asad who was called Umm Yaqub, and she used to recite the Quran. She came to him and said: "What is the news that has reached me from you that you curse those women who have themselves tattooed, the women who pluck hair from their faces, and for beautification changing what Allah created?"
Thereupon Abdullah said "Should I not curse one upon whom Allah's Messenger invoked curse, and that is in the Book also?" Thereupon the woman said "I read the Quran from cover to cover, and I did not find that in it" Whereupon he said "If you read (thoroughly) you would have definitely found this in that as Allah said:
"What Allah's Messenger brings for you accept that, and what he has forbidden for you refrain from that" (72).
The woman said: "I find this thing in your wife even now." Whereupon he said "Go and see her" She reported. "I went to the wife of Abdullah and found nothing of this sort in her" She came back to him and said "I have not seen anything" Whereupon he said "Had there been anything like that in her, I would have never slept with he in her bed" (Related by Bukhari and Muslim).