Cultural norms are underpinned by religion as well. For example the west, as scholars like Tom Holland would argue, has been so steeped in Christian values that westerners do not even realise this anymore.
In like manner, these cultural norms are underpinned by Islam. On nothing in the Quran permitting honour killings or physical attacks, may I refer you to Surah 18, where a young child is killed justifiably because he would grow up to become a disbeliever (Vs 65, 74,80).
More expressly, in the Hadith, the prophet says,
"Whoever changes his religion, kill him"
(Sunan An-Nasai 4059)
To show you how this was interpreted by the earliest companions,
Narrated `Ikrima:
Some Zanadiqa (atheists) were brought to `Ali and he burnt them. The news of this event, reached Ibn `Abbas who said, "If I had been in his place, I would not have burnt them, as Allah's Messenger (ﷺ) forbade it, saying, 'Do not punish anybody with Allah's punishment (fire).' I would have killed them according to the statement of Allah's Messenger (ﷺ), 'Whoever changed his Islamic religion, then kill him.'"
(Sahih Bukhari 6922)
Then you have Surah 9:29,
"Fight against those who (1) believe not in Allâh, (2) nor in the Last Day, (3) nor forbid that which has been forbidden by Allâh and His Messenger Muhammad (صلى الله عليه وسلم) (4) and those who acknowledge not the religion of truth (i.e. Islâm) among the people of the Scripture (Jews and Christians), until they pay the Jizyah with willing submission, and feel themselves subdued."
The next verse tells you why...it is because the Christians say Jesus is the Son of God and the Jews allegedly say Ezra is the son of God. Which no Jew has ever said.
And there is plenty more where that came from.
Still think the Quran has nothing to do with it and that Islam is a religion of peace?
Bearing in mind Surah 47:35 specifically tells adherents if islam not to sue for peace when they have the upper hand. Hence the religion tends to be super violent in locations where they are the majority.
Does this suffice?
