That could be an interesting one to make yourself, if a bit challenging.
Goodbye To Magic (GTM or sometimes known by it's street name of 'Grease The Mage') being a policlub advocating against the use of magic, blaming it and it's users for many of the world's woes such as:
(Please remember some of the following are not actually Magical, but could still be spun by a good PR guy as such. )
Break up of the good old USA, no GGD or other Indian shenanigans would have meant the old stars and stripes would still be flying sea to shining sea...
Goblinization. It's not your fault you became an orc, it's those bloody wizards. Someday we will find a cure to make you 'normal'
VITAS, spun as a magically mutated threat.
(Nothing like global epidemics to help throw blame around..)
Spirits. Angels or devils? Either way, man has no reason to traffic with either...
Technomancers or 'Digital Mages threatening us from the Matrix'.
(Again not really, but these guys just do not see the difference between Resonance and Magic. They just see spooky stuff happening they can not explain
Plus it pisses the TM's to no end being lumped together with the mages. )
and by extension...
Infected, spun as a magical parasite feeding on the living, turning loved ones into monsters.
(The fact that a number of Infected have a high chance to manifest as mages once Infected doesn't help..)
Bugs
Shedim
So who would join this sort of group?
Many members are drawn from families who have lost loved ones to Magics / Infected / Bugs, etc... Lost souls seeking some way to make sense of their tragic loss...
Embittered armchair generals who dream of a bygone era.
Burnt our mages
Surprisingly you see some among the flock. Bitter about what they once had and blaming everyone but themselves.
These guys also serve as useful sources with how to deal with other mages.
The group's public face calls for tighter restrictions on licensed magic use and harsher penalties for illegal use of magic/technomancy with the aim being a total boycott of same.
They will likewise lobby bitterly against anything resembling a recognition of rights for spirits or Awakened/Emerged critters.
Some will insinuate themselves into schools, hospitals and other social care networks keeping an eye for young awakened/emerged to try and convince them that their gift is somehow a sin and that they must deny it.
They may also fund research into trying to pin down the 'magic' gene, not to turn it on but to figure out how to turn it off.
The shadowy side of this policlub looks for a more hands on approach to the magic threat, but this can be a challenge since you are hunting someone who can rain fire down and summon creatures from beyond and you sort of deny magic so that option is out. Some have worked their way into penal facilities and in some areas the number of awakened fatalities in correctional facilities has been on the rise. Again the members working in hospitals would be well placed to switch out babies born of magical parents in the hopes of snipping the bloodline.
For actual attacks Sniping attacks are preferable, but for up close most attacks open with some sort of blinding action as you can not cast at what you can't see.
Rumors of Nega-mages and similar have been floating around and this can be a fun way to introduce these to a campaign.