Members of the First United Methodist Church in Tellico Plains, were talking about recent shootings at places of worship when the 81-year-old pulled out a .380-calibre ruger handgun to show another parishioner.
Police said he removed the magazine, cleared the chamber, and showed the gun, before putting the magazine back in and returning the gun to its holster.
However, he forgot the gun was loaded and when someone from the Thursday afternoon Bible-study group asked if they could see it, he brought it out saying it was not loaded and pulled the trigger.
The bullet sliced the man's palm before it entered the left side of his 80-year-old wife's abdomen and exited the right side, as she was sitting in her wheelchair.
The couple were taken to hospital with non-life-threatening injuries.
A parishioner who only wished to give her first name, Mistin, told the BBC the injured man is a lifelong gun-owner who practises every week.
But she claimed he's been so traumatised by the incident that he plans to get rid of his weapons.
Speaking about the couple, Mistin said: "They're just true servants of the Lord, they're such a delight.
"We thank God. I don't know how God's using this but we put it in His hands."
