The recent Christchurch killings was deliberately designed to use social media to demonstrate that no place is safe from ideological supremacists and their plans.

The name Christchurch and the target of a mosque – From things read it seems that the killer was familiar with and demonstrating activities relating to the crusades.
Religious wars (like are frequently driven by minority supremacists on all sides of religious conflicts – not the majority. The intent of the supremacists is to distort religious messages and texts for their own purposes.

Currently, such supremacists have many Internet tools to assist them in spreading their messages. This is what appears to be the case in the Christchurch killings. People need to learn from digital citizenship principles for social media and how they apply to what happened. One of many analyses is given here