What does the name Jehovah Nissi mean that Moses gave the altar in Exodus 17:15?
Jehovah Nissi translates as "He is our banner." Moses gave this name to the altar after Israel’s conflict with Amalek to acknowledge that God Himself fought the battle, using Israel’s men but controlling the outcome. The banner is like a flag or marching flag, showing God’s leadership and victory on behalf of His people.
Les explains that Moses built an altar after the battle and called it Jehovah Nissi, which translated means, "He is our banner." In other words, today we might call it our flag, our marching flag. The point is that God fought the battle against Amalek; Israel's men were used, but as long as Moses' arms were held up, the battle went Israel's way, and if they fell, it went against them. Therefore, the name confesses that God was in control and was Israel's banner. Les also connects this to Zechariah, where the Lord, Jehovah in the Old Testament and Christ in the New, will fight against the nations as when He fought in the day of battle.
And Moses built an altar, and called the name of it Jehovahnissi: