That is how one might perceive symbolically that the woman who felled of Abimelech represents God's people.

The strong tower she is on one perceives perhaps is the LORD God as he is protecting her, his people, as is exemplified by David who says as Lord to the LORD God in Psalm 61:2-3 “From the end of the earth will I cry unto thee, when my heart is overwhelmed: lead me to the rock that is higher than I. For thou hast been a shelter for me, and a strong tower from the enemy.”. This would seem also to be demonstrated by Solomon the son of David in Proverbs 18:10 “The name of the LORD is a strong tower: the righteous runneth into it, and is safe.” And it is appropriate that David speaks of these things because it is a promise of God through his new covenant by its mediator Jesus Christ that the sure mercies given to David as Lord,the son of man, and a son of God and not just a man as was seen as he sat before the Mercy Seat of the Arc of the Covenant in the Holiest of Holy places  (2 Samuel 7:18) if in fact he sat there to confimr the promise which is not lawful for a man to do and is a capitol offense for a man unless he is the High Priest cleansed to enter in once a year to make an atonement offering for the people of Israel, as seen when through prayer he confirmed that God's prophecy of Messiah should be fulfilled when the prophecy was given to him, and from whose line the Messiah, the Lord Jesus Christ, descends from, that these mercies would be extended to God's people in the new covenant of Jesus Christ. It is in this covenant through Jesus Christ in which God's people are received as son's and daughter's of God as is spoken by Isaiah 55:53-54 “Incline your ear, and come unto me: hear, and your soul shall live; and I will make an everlasting covenant with you, even the sure mercies of David. Behold, I have given him for a witness to the people, a leader and commander to the people.”

The piece of millstone that is cast down from the tower, one might percieve is a rock which symbolizes the Lord Jesus Christ. In-fact, Jesus is referenced many times throughout the Bible as a “Rock” and as a “Stone”. Daniel centuries following the time of Judges in the time of Captivity of the nation Judah (Daniel 2:19-44), tells Nebuchadnezzar, the king of Babylon, the king's own dream along with its interpretation. In that telling, though Daniel at the time doesn't realize this (Daniel 12:8 affirms this), the rock in Nebuchadnezzar's dream which fills the whole earth is Messiah, Jesus Christ. Jesus is alluded to also as this stone in Zechariah 3:9 “For behold the stone that I have laid before Joshua; upon one stone shall be seven eyes:”, in Isaiah 8:14 “And he shall be for a sanctuary; but for a stone of stumbling and for a rock of offense to both the houses of Israel, for a gin and for a snare to the inhabitants of Jerusalem.”, and in Luke 20:18 “Whosoever shall fall upon that stone shall be broken; but on whomsoever it shall fall, it will grind him to powder.”