Gideon was chosen by the Lord to lead the Israelite people to freedom. The Lord had Gideon show his allegiance to God by first destroying the altar of the false god and to then offer a sacrifice. 
This is yet another reminder of what our life should like. We should constantly be denying our flesh (tearing down false gods) and choosing the will of the Lord (offering a sacrifice).
Look to Jesus, to the Word, for guidance.
Scripture taken from:

Judges 6:24-27