Again, if you read the Christchurch shooter's manifesto, the objective here is to start a war in the US, any way they can, to get the Government here to try to take away our RKBA, and to incite serious problems between gun owners and the Government here. It struck me as strange that the guy was shooting Muslims in NZ to do this, but he also mentioned (correctly) that the Kiwis would lose their guns over the incident. He described NZ as "lost", but expected violence in the US if such measures were taken by the government here against the RKBA.
Mosques, Synagogues, Churches, any soft target that will cause an outcry, across religious and racial lines, are targets for this type of 'movement', aimed at providing ammo to the anti-gun factions in the US and elsewhere where there is still an RKBA, for the purpose of fomenting a greater conflict.
These incidents are part of a larger pattern of instigation attempts.