We need to understand the Koran’s exhortations

These men were not cowards. They knew they would be hailed as martyrs by their leaders and sympathisers. To a civilised person this is a despicable perversion of the word, but they believe it strongly enough to die and kill for it.
But to denounce the cruelty while denying the reality of the religion behind it is to strike at the fruit while leaving the root unharmed.