How do you fight a cult, then?
If the cult is a harmless bunch of people who believe nonsense, you let them alone.
If the cult is a bunch of freaks who teach and practice jihad, you punish them as appropriate and deport them out of the country if they are active in preaching, teaching and recruitment.
If they are harmless and aren’t preaching and teaching Sharia and jihad, let them alone.
And Arabic speaking minders should be attending every mosque function in the country.