How did Gideon respond to God's call?

After asking for a sign to make sure God would aid him, he obeyed God, destroying an idolatrous altar and gathering an army to fight the Midianites (Judges ch.6-7). He was called Yerubaal, alluding to his having destroyed the idolatrous altar of baal (Judges 6:31-32). See also:

Monotheism in Judaism