Whenever you encounter someone who buys into Homeopathic cures, you should give them the Homeopathic Challenge. Tell them to induce severe Alcohol Poisoning by chugging an entire bottle of Everclear (a 190 proof grain spirit) in one go. They should then place 1 drop of Everclear in a liter of distilled water, mix it up, and dilute it down further as necessary. If Homeopathy really works, this solution should cure the Alcohol Poisoning and save the guys life. Obviously drinking an entire liter of such potent liquor will mean death without medical treatment, so you can use this to entice the retard to prove once and for all Homeopathy works.