It's claimed that Thai macaques are a protected species, clearly not in danger of extinction. Sterilisation means that each male monkey has to be 'darted' with a drug to render it unconscious, then 'snipped', recovered and released. All in all a protracted process. I suspect the beasts will reproduce faster than that programme can diminish their numbers.
Cast aside religious 'concerns' and plan a mass extermination programme which, practically, will require poisoning and cremation or burial. Local people who have to live with these pests will force the issue. Animal loving protesters who do not have to personally suffer the daily nuisance of these animals can join a BookFace group of concerned netizens and focus their protests on foreigners committing illegal acts.