This was the statement they made:
In a blessed attack for which Allah facilitated the causes for success, a faithful group of the soldiers of the Caliphate, may Allah dignify it and make it victorious, launched out, targeting the capital of prostitution and obscenity, the carrier of the banner of the Cross in Europe, Paris
Youths who divorced the world and went to their enemy seeking to be killed in the cause of Allah, in support of His religion and His Prophet, Allah’s peace and blessings be upon him, and his charges, and to put the nose of His enemies in the ground. So they were honest with Allah, we consider them thusly, and Allah conquered through their hands and cast in the hearts of the Crusaders horror in the middle of their land, where eight brothers wrapped in explosive belts and armed with machine rifles, targeted sites that were accurately chosen in the heart of the capital of France, including the Stade de France during the match between the Crusader German and French teams, where the fool of France, Francois Hollande, was present
[They also targeted] the Bataclan Conference Center, where hundreds of apostates had gathered in a profligate prostitution party, and other areas in the 10th and 11th and 18th [arrondissements] and in a coordinated fashion. So Paris shook under their feet, and its streets were tight upon them, and the result of the attacks was the death of no less than 100 Crusaders and the wounding of more than those, and unto Allah is all praise and gratitude
Note 'the capital of prostitution and obscenity' 'apostates' 'crusader teams'
Why will people not believe they are killing people for the reasons they are SAYING they're killing them
While the Western influence may play a part, it is not the reason
The reason is that they want to create a caliphate and will attack anyone who tries to stop them.