From Wikipedia

God's Gun (also known as Diamante Lobo) is a 1976 Spaghetti western directed by Gianfranco Parolini and starring Lee Van Cleef. Jack Palance plays the head of a malicious group of bandits and Van Cleef plays a double role of brothers, a priest and a reformed gunfighter, determined to stop them.

Leif Garrett also plays a vital part in the film, as a fatherless kid who brings the reformed gunfighter to town.

God's Gun was filmed in Israel.

Plot

Aaron Harrison (Lee Van Cleef) is a priest preaching in the small town of Talpaca, referred to by the citizens as "Outer Heaven" and also known as "Juno City" [1]. Outer Heaven is a place where mercenaries come as a sort of neutral spot where they can relax and live. One day the leader of the thieving Clayton gang, Ben Haenni (Jack Palance), comes to town and cause trouble, stirring up the frail political bonds that hold the town together. Ben goes on to challenge the leader of Outer Heaven know simply as The Boss, the top mercenary. Aaron, seeing violence spread across the town as the two factions wage war, sacrifices himself in an explosion to save both The Boss and Ben as they are about to kill one another. Touched by the sacrifice, the two part ways, remembering the lesson taught that day.