Red Headed Stranger (1986)

The Rev. Shay (Willie Nelson) moves out West to set up his new home in Montana so that he can spread God's word. But when his wife, Raysha (Morgan Fairchild), leaves him for another man -- in part because she wants to return to Philadelphia -- the reverend decides to replace his spiritual ways with a gun. After shooting down his wife and her lover, he battles a landowner intent on keeping all of the town's water for himself. But his deadly ways make him yearn for a belief in God again.