It is Left wing terrorism along with the threat of Islam that is the threat....which continues to grow.
Nor is it a systemic problem in any country. The Christchurch cases gets a lot of media coverage because it fits the Left's false narrative of "Muslims as victims of racism" and because it is a freakishly rare "man bites dog" story.
Meanwhile, terrorist attacks BY Muslims occur around the world on a weekly basis and are mostly a footnote. These include recent attacks against Christian Churches in Egypt, the ISIS-inspired Church bombing in the Philippines, and the Dutch shooting all happened within weeks of Christchurch, but received far less media coverage.