As we look through the history of the Bible, when people are captured by a false idea or enslaved by a tyrant, God speaks to a single person, flawed by imperfection, who hears the unmistakable call of God.
Moses was at work keeping the flock of sheep under control for his father-in-law Jethro when his call came. The strangeness of the bush which did not burn up caused Moses to turn aside. The call of God has two sides to it, the voice of God and the willingness to hear God calling us by name. In the beginning Moses made excuses. I can not do what you ask. Yet God did not give up on Moses. When God calls to you will you yield to his will?