The shooter, Brenten Tarrant, is a coward who slaughtered innocent defenceless people. Even if the mosque was linked to extremist activities, the people who lost their lives should not have suffered in that reprehensible way. It was misguided outrage, perverted justice, utterly disproportionate and shameful. It is so far removed from any notions of reasonableness, even in a legitimate war, such actions are universally condemned.
He is not a firebrand nor is he a maverick - doing what others are too timid to do - as some have claimed. His actions and legacy will not change policy, rather, they will further polarize the population against the hard right, in all its flavours. They will serve as a convenient excuse to tighten every conceivable law pertaining to gun ownership, speech, and freedom of association.
You may exult him as a hero but this is due to your personal position in society situated comfortably on the lowest rung. If there was a button to destroy the world, you'd push it out of pure resentment and spite.
Jews aren’t to blame for your position, the Muslims aren’t to blame, and women aren’t to blame. It's more complicated than blaming these groups for your lot in life. Life is not fair, some are more intelligent than others, some are born into wealth, some have more influence to propagate their ideas, and life is a struggle. But this is not an excuse to commit acts of murder on innocent victims.
If you don’t agree with left policy and you think certain things are unacceptable, get involved in politics. Seek out the members of government who are for the same things you are and let them know you support them. Channel your energy into politics. Expose your ideas, however extreme they may be, to others and you can see where you’re right and where you’re wrong.
More importantly, if you feel hopeless and things are against you, seek out a psychologist for therapy, it's never too late to turn it around.