But Moses again pleaded, “Lord, please! Send anyone else.” Then the Lord became angry with Moses. “All right,” he said. “What about your brother, Aaron the Levite? I know he speaks well." Exodus 4:13-14 (NLT)
God called Moses to lead his people out of Egypt. WOW! Can you imagine how overwhelming that thought might be? I think anytime God calls us to do anything, it would make us draw back and think about it. His plans are, well, God-sized which is magnificently bigger than ours.
Moses was overwhelmed. It seemed impossible. So he asked for an out. "I can't", he said. God said, "You can, I will be with you." "I don't have the right skills," Moses said. God said, "I will give you the skills you need." "Please, send someone else anyway." God said, "Alright, I'll let Aaron help you."
Moses didn't see, maybe couldn't see, what God saw. God saw in Moses a history and experience that would help him. God saw in Moses leadership qualities. And finally, there was the relationship between them which counts for more than all of the above. Aaron didn't have those same qualities. As a matter of fact, under Aaron's leadership Israel built the golden calf to worship at the base of Mt Sinai.
God grew Moses to be the leader he needed to be. He walked him every step of the way. The man who said "I can't" ended up being one of the pivotal people in our history.
Is God calling you to something? It may not be as high profile as Moses' task. It may be something that seems rather small but to you it is overwhelming. Keep talking to him. Maybe instead of saying "God, I can't" we can say "God, show me how."