I love the story of Moses. God calls Moses to meet the needs of His people. Moses responds with doubt, questions and uncertainty. But he soon realizes that God's call has very little to do with his doubt. God's call is always related to the cry of His people (everyone that walks the face of the earth). God hears our cry and meets our need. 

“The Israelites groaned in their slavery and cried out, and their cry for help because of their slavery went up to God. God heard their groaning and he remembered his covenant with Abraham, with Isaac and with Jacob. So God looked on the Israelites and was concerned about them.” Exodus 2:23-25