The event I have in mind is from Exodus 17:8-16. The Amalekites have come up to attack the Israelites at Rephidim. Joshua is sent out to fight, and Moses goes to the top of the hill where he lifts up 'the rod of God' above his head. And as long as Moses held the rod up, 'Israel prevailed', but when his arms grew weary and he let the rod down, 'Amalek prevailed' (Exodus 17:11). So Moses ends up sitting on a stone with Aaron and Hur holding his arms up in the air.
Now, that's all very dramatic; but what's going on. Surely Israel doesn't win because Moses holds a stick in the air? That sounds rather like magic, which is not how the God of the Bible works. So what on earth does Moses holding up the rod have to do with victory?
Well, this isn't any old rod. It's not some magical act brought about through a piece of wood. This is a very particular rod. It's been used again and again in the book of Exodus. In fact, it gets passed about a bit between Moses and Aaron, but Exodus 17:5 makes it clear that they've both been using the same rod (it was Aaron's rod that struck the River Nile in Exodus 7:19-20). This is the rod that God turned into a snake and swallowed up the snakes of the Egyptian magicians. This is the rod that God used to bring the plagues, those judgements on the gods of Egypt. This is the rod that God used to part the Red Sea to deliver the children of Israel from the land of bondage. This is the rod that God used to bring that waters of the Red Sea back in upon the armies of Egypt, bringing judgement upon His enemies. And this is the rod which God used to bring the waters of life to the people from out of the Rock, by striking the Lord Christ (Exodus 17:6). This was certainly not just any old rod.
This rod was the sign of God's deliverance and God's judgement. And this rod was the sign of God's grace. It wasn't a magic wand, but rather a powerful sign of the victory of God.
But the power didn't reside in the rod or in Moses arms. Just like the saving power didn't reside in the lambs slain on the night of the Passover. No, the power could only be found in what the rod pointed to.
So, what did the rod point to? Not just to grand themes of judgement, deliverance and grace, but to God's great act of judgement, deliverance and grace. The rod was the wood which pierced the LORD as He stood between Moses and the Rock (Exodus 17:6), and that piercing wood points us to the great piercing wood; it points us to the Cross, where Christ the LORD would be pierced to bear the judgement for the sins of the world to bring God's deliverance to His people by His grace. The rod speaks to us of the Cross (by which, of course, we mean more than the wooden beams, but more precisely Christ and Him crucified).
As Moses raised up the rod, he was raising up the sign of God's judgement, deliverance and grace. And we too raise up the rod today when we lift up Christ and Him crucified: the One who bore God's judgement, bringing us deliverance and grace.
There's a bit more about this battle that isn't to do with the rod, but we'll save it for another day.