Two antisemitic extremists wrote a manifesto blaming Jews for everything, then tried to shoot up a mosque. Which is either spectacularly ironic or says something about how sloppy and improvised these operations actually are. Either they couldn't tell the difference, didn't care, or just grabbed the first place of worship they could hit. Either way, the manifesto reveals where their hatred pointed. The target confusion doesn't make it less of an attack - it just makes it stupid.