The Persuader.

In one of his rare movie starring assignments, William Talman (Hamilton Burger on TV's Perry Mason) plays a dual role in The Persuader. Talman is seen as gunslinger Matt Bonham and his twin brother, preacher Mark Bonham. When Mark is killed by outlaw leader Bick Justin, Matt takes his brother's place in the pulpit, ramming the Fear of God down the throats of the wanton townspeople. Impressed by Bonham's courage, the townsfolk begin to follow the straight and narrow path.