The court agreed religious convictions did not trump the British Columbia man's lack of medical skills and proper equipment.
The appellant, whose name was not reported, was convicted of criminal negligence and assault in the 2007 incident in which he gave his son 4 ounces of homemade wine as an anesthetic and then attempted to remove the foreskin with a carpet knife purchased at Home Depot, the St. Catherines (Ontario) Standard reported Saturday.
The surgery resulted in a lot of bleeding, which was staunched with paper towels and a veterinary compound.
The man told authorities he performed the surgery to "make things right with God."
Prosecutors said he should have known better because he had tried the same procedure on himself two years earlier and wound up in the hospital.