Chapter 9 is the longest chapter in the book of Judges, and one of the most depressing. Abimelech was not raised up by God as a deliverer, and did not produce any deliverance. This reminds us of the awesome consequence of choices. Gideon acted like a king by having many wives, and wanting even more he had a concubine with whom he had this son whom he named Abimelech, "my father is king".
Abimelech is a type of the ambitious carnal man grasping for power and leadership among God's people. The early church started with humble shepherds. How did we get from there to people bowing down and kiss a pope's hand?
Instead of associating with the spiritual descendants of Gideon, Abimelech associates with his carnal brethren. Where do we find our fellowship?
Abimelech needed financing, so he took tribute of 70 pieces of silver and hired a mob. The money came from an unclean source, and is used it for a tragic purpose. Abimelech hires a mob of vain and unstable men to go to his father's house slay his 70 brothers. He calls his father by the name Yerubba'al rather than Gideon, reminding the worshippers of Ba'al that his father is the one who pulled down the altars of Ba'al.
This youngest son managed to escape. His name is Yotham, which means YHWH is Perfect. So often it seems like evil is ready to triumph and the righteous close to being exterminated, but God always finds a way to preserve His remnant.
Yotham came out of hiding and stood atop mount Gerizim, giving the first parable in Scripture. The trees are men. The fruitful trees included Gideon, who refused kingship, and the bramble included Abimelech who grasped at kingship.
It's really important for us to pray earnestly for God to raise up spiritual men who love the Lord and His Word. Men who love the flock, who care and see the value of God's flock, and are willing to pour their life into divine service in ministering to God's people. How desperately we need such men.