No flesh should glory in His presence(1 Corinthians 1:29). This verse is not just a New Testament truth—it was true in Moses day, as well. Moses could not deliver God's people in his own strength. He had to be taught, once and for all, that God's work is done not through any human ability but by total trust and dependence on the Lord.
This is true for every Christian today. There has to be a putting off of all that the flesh tries to bring to God. Indeed, God says to us as He did to Moses, "There is only one ground upon which you can approach Me, and that is holy ground. You can have no confidence in your flesh because no flesh will stand in My presence!"
When talking to Moses, God put a focus on shoes (see Exodus 3:5) because our feet are two of the most tender parts of our body. And what are shoes, but a protection of our flesh? They protect us from the elements, from stones, from snakes, from filth and dust, from the hot pavement.
Do you see what God was saying to Moses here? He was using an everyday, ordinary thing to teach a spiritual lesson, just as Jesus later did when He used coins, pearls, camels and mustard seeds. God was saying, "Moses, you wear protective garb to keep your flesh from injury. But no amount of fleshly protection will be able to keep you when I send you into Egypt—that den of iniquity—to face a hardened dictator. You will be put into a situation that only I can deliver you from. So, unless you set aside all reliance on your flesh—your meekness, zeal and humility—you won't be able to do what I'm calling you to do. All your abilities will be worthless unless I sanctify them."
Indeed, Moses faced all kinds of tests and trials as he led some three million people into the desert. With no grocery stores, malls, or even a well of water, he had to depend wholly on God for everything.
Moses had already tried to act as a deliverer in the power of his flesh. Forty years earlier, he had taken sword in hand and killed a cruel Egyptian slave driver. And now God was saying, Moses, your zeal has to be sanctified or it will destroy you. Are you willing to put down your sword and place all your confidence in Me?