Chinese martyr Watchman Nee said that God had to teach him when to speak up and then when to shut up. Serving God is not always a matter of using personal judgment, but of listening for His direction. This is true for everyone and was even true for Moses.
As the Israelites multiplied greatly in Egypt, the current Pharaoh enslaved them because he didn’t want them to become strong enough to leave. He also tried to have the male babies killed, but the midwives refused to cooperate and when Moses was born, his mother hid him in a basket at the edge of the Nile. He was found and adopted by a princess, yet God's providence allowed him to be nursed and raised by his own mother.
As a grown man, he saw the oppression of his people and tried to help one of them by killing an Egyptian oppressor, but Pharaoh found out and he fled for his life.
Many years later, when Moses was 80 years old, God revealed Himself to Moses as I AM. After a long conversation God finally convinced Moses back to win the freedom of his people. God gave him miraculous signs and the help of his brother Aaron, yet Moses was fearful and reluctant thinking that no one would listen to him.
The Lord said, “Come, I will send you to Pharaoh that you may bring my people, the children of Israel, out of Egypt.”
But Moses said to God, “Who am I that I should go to Pharaoh and bring the children of Israel out of Egypt?”
God said, “But I will be with you, and this shall be the sign for you, that I have sent you: when you have brought the people out of Egypt, you shall serve God on this mountain.”
Without reading the entire story, Moses sounds like a humble man who feels undeserving to be given this task. But that is not his problem. He tried to liberate one of his people once and wound up running for his life. That was many years ago, but he knew the history in Egypt; the Pharaoh was an oppressor with a large army and lots of power. All Moses could think of was his own inadequacy and the size of the challenge.
Throughout chapters 3 and 4, God keeps diverting this man's focus to His power and His adequacy. Finally He became angry at the excuses Moses offered. . .
But Moses said to the Lord, “Oh, my Lord, I am not eloquent, either in the past or since you have spoken to your servant, but I am slow of speech and of tongue.”
Then the Lord said to him, “Who has made man’s mouth? Who makes him mute, or deaf, or seeing, or blind? Is it not I, the Lord? Now therefore go, and I will be with your mouth and teach you what you shall speak.”
But he said, “Oh, my Lord, please send someone else.”
“Then the anger of the Lord was kindled against Moses and he said, ‘Is there not Aaron, your brother, the Levite? I know that he can speak well. Behold, he is coming out to meet you, and when he sees you, he will be glad in his heart. You shall speak to him and sput the words in his mouth, and I will be with your mouth and with his mouth and will teach you both what to do.’" (Exodus 4:10-15)
As I think about this, I recognize the danger of trying to go ahead of God, or to do anything, great or small, apart from His direction or help. What Moses did earlier in killing the Egyptian, right or wrong, should have taught him that self-effort does not work. Instead, it made him fearful, so much so that he repeatedly says 'no' to any challenge, even from Almighty God. He could not get his thoughts off his own failure nor could he focus on the fact that the God of the Universe would give him all he needed to do the job. His self-effort to do the job should have taught him to rely on God, but instead played a part in setting him up for disobedience.
I'm almost shaking as I remember all the times I've been like Moses. Ambition and zeal have pushed me into doing what I think is God's will only to later find out that my motivations were more about my own ideas and that I was not relying on Him as I should. For the most part, God did not throw egg on my face, but I came out of these episodes with a greater sense of my own failure. This is a good thing -- as long as it isn't one more excuse to make life all about me. That is what Moses did, and that is what made God angry with him.
The good news is that God knows what to do with those whose zeal makes for hasty choices and whose fear causes huge reluctance. Through the challenges, Moses eventually realizes that he is serving a God for whom nothing is too hard, and whose strength is perfected in our weakness!