It's the Plan 9 From Outer Space of Christian Movies: If Footmen Tire You, What Will Horses Do?
The director, Ron Ormond, made a bunch of cheap exploitation films in Hollywood before finding Jesus in the message of Mississippi evangelical reverend Estus T. Pirkle. Why? I have no idea. He's not especially charismatic and he sounds like an idiot.
But Ron moved down to Mississippi and decided to keep making exploitation movies, but make them Jesusy. He made four of them with the Rev, but that one is the funniest.
Also, there was an LP version of Pirkle's sermon delivered in the film. That version was sampled by the band Negativland for what is probably the song they're most well-known for, Christianity is Stupid: https://www.youtube.com/watch?v=Vrt6o81ku5o