"And the Angel of the LORD appeared to him in a flame of fire from the midst of a bush. So he looked, and behold, the bush was burning with fire, but the bush was not consumed. Then Moses said, 'I will now turn aside and see this great sight, why the bush does not burn.' So when the LORD saw that he turned aside to look, God called to him from the midst of the bush and said, 'Moses, Moses!' And he said, 'Here I am.' Then He said, 'Do not draw near this place. Take your sandals off your feet, for the place where you stand is holy ground'" (3:2-5). Moses had seen many things during his decades as a shepherd, but this was new! He had to investigate this bush that was on fire yet was not consumed. As Moses approached, the Angel of the LORD (who, as the context shows, is God Himself) spoke to Moses from the fire and explained to him that he was in God's presence and should behave accordingly. Moses reverently took off his sandals and watched and listened with a growing sense of awe and terror.
"Moreover He said, 'I am the God of your father--the God of Abraham, the God of Isaac, and the God of Jacob.' And Moses hid his face, for he was afraid to look upon God. And the LORD said: 'I have surely seen the oppression of My people who are in Egypt, and have heard their cry because of their taskmasters, for I know their sorrows. So I have come down to deliver them out of the hand of the Egyptians, and to bring them up from that land to a good and large land, to a land flowing with milk and honey, to the place of the Canaanites and the Hittites and the Amorites and the Perizzites and the Hivites and the Jebusites. Now therefore, behold, the cry of the children of Israel has come to Me, and I have also seen the oppression with which the Egyptians oppress them. Come now, therefore, and I will send you to Pharaoh that you may bring My people, the children of Israel, out of Egypt" (3:6-10).
As God described the suffering of the Israelites and His intention to free them from slavery and bring them to Canaan (the exceedingly blessed land He had promised them), I suspect Moses figured out where this conversation was going. And, if for some reason he didn't "connect the dots," God explicitly tells Moses what He desires of him. He wants Moses to be the leader of the exodus! God had been preparing him for this moment, though Moses, as we will see, is very reluctant to take on this task. Previously he had wanted to be a liberator, but now he is 40 years wiser and much more cautious. He has learned humility and no longer trusts his own power and fitness.
"But Moses said to God, 'Who am I that I should go to Pharaoh, and that I should bring the children of Israel out of Egpyt?' So He said, 'I will certainly be with you. And this shall be a sign to you that I have sent you: When you have brought the people out of Egypt, you shall serve God on this mountain'" (3:11,12). Moses' first words were not: "Here am I! Send me" (Isa. 6:8). Rather, he begins asking God questions--questions of doubt. "Am I really the right one for this job, God?" It may not be troubling to ask a question like this to a fellow human being, wondering if they have made the best choice in selecting you for an important task. However, making an inquiry like this to an all-powerful and all-knowing God is both unwise and insulting. There is a sense in which Moses' question implies of God: "Do you really know what you're doing?" God encourages Moses and is content to bear with his reluctance for now, but, as the dialogue unfolds, we will see His patience does have a limit. God eventually gets angry with those who show a reluctance to embrace responsibilities He has assigned them.