The Battle with the Philistines
Now, as we have already explained, this battle happened before hand when David met Goliath and freed the people from his tyranny (1 Kings 17), because Christ also dueled the devil and saved the people who had been oppressed by him.
The Philistines were making war on Israel, and the host of demons was waylaying the human race; their enemies had sent troops against the people of God, and the devils raised up tyrants against the just; the enemies were protected by a wall, and the demons refined their wiles through the philosophers and poets. Goliath taunted God’s armies, and the devil mocks God’s devout through idolatry. David is sent into battle by his father, and Christ is dispatched into the world to wage his contest. David pastured sheep, and Christ led the flock to the fields of life. David defeated a bear and a lion, and Christ overcame the devil’s temptation. David left his sheep and hasted to the place of battle, and Christ, deserted by his disciples, came into the enemy’s assembly place.
At David’s arrival there was great shouting in the camp, and when Christ came among the Jews the cry went up “He deserves to die!” David puts on Saul’s suit of arms, but takes them off again (I Kings 17), and Christ is dressed in Pilate’s military uniform, i.e. the royal purple and the scarlet mantle, then stripped of them immediately . David carried a staff against the Philistines, and Christ carried the cross against the devil. David took a milk bucket, and Christ took a jar of vinegar. The enemy is toppled by a sling and stone, and the devil is beaten by Christ’s flesh. For we should understand the sling to be Christ’s flesh, the stone his soul, and David his divinity. The stone hurled by the sling pierces Goliath’s skull because Christ’s soul, driven from his flesh by cruel torture, invaded and despoiled the tyrant’s dominion of Hell. He kills him with his own sword, because by his death Christ conquered the author of death. The people rejoice at David’s return, and the faithful people celebrate Christ’s return from Hell. David is received by singing crowds on his way back to Jerusalem, and in Christ’s ascent from Jerusalem into the heavens he is met by the angels singing hymns of praise.
 1 Samuel 17:38-40:
Saul clothed David with his armor; he put a bronze helmet (galea) on his head and clothed him with a coat of mail (lorica). David strapped Saul’s sword over the armor, and he tried in vain to walk, for he was not used to them. Then David said to Saul, “I cannot walk with these; for I am not used to them.” So David removed them. Then he took his staff in his hand, and chose five smooth stones from the wadi, and put them in his shepherd’s bag, in the pouch; his sling was in his hand, and he drew near to the Philistine.
CAP. LXXXI. – De pugna Philistaei.
Hoc ut dictum est in figura praecesserat, quando David cum Goliath congressus populum a tyrannide eius eruerat (I Reg. XVII), quia et Christus cum diabolo duellum subierat et populum oppressum ab eo eripiebat. Philisthim namque Israel impugnabat, et daemonum caterva humanum genus vexabat; hostes contra populum Dei aciem direxerant, et daemones contra iustos tyrannos incitaverant; hostes se vallo munierant, et daemones per philosophos et poetas errores firmaverant. Goliath agminibus Dei exprobrabat, et diabolus cultoribus Dei per idololatriam insultabat. David a patre suo ad pugnam mittitur, et Christus a Patre in mundum ad certamen dirigitur. David oves pavit, et Christus innocens ad pascua vitae congregavit. David ursum vel leonem superavit, et Christus diabolum se tentantem superavit. David ovibus derelictis ad locum certaminis tendit, et Christus a discipulis derelictus ad conciliabula hostium venit. Veniente David clamor in castris oritur, et Christo inter Iudaeos veniente clamor reus est mortis exoritur. David a militibus armis Saul induitur, moxque eisdem exuitur (I Reg. XVII), et Christus a militibus vestibus Pilati, scilicet purpura et Chlamide coccinea induitur, moxque eisdem exuitur. David contra Philistaeum baculum portavit, et Christus crucem contra diabolum baiulavit. David mulctrum, et Christus accepit vas aceto plenum. Hostis funda et lapide prosternitur, et diabolus Christi carne vincitur, Per fundam quippe, Christi caro; per lapidem, eius anima, per David, deitas intelligitur. Petra itaque de funda excussa frontem superbi penetrat, quia anima Christi, de carne tormentis excussa, regnum tyranni penetrans infernum spoliat. Proprio ense victum iugulat, quia per mortem auctorem mortis vicit. Reverso David populus laetatur, et Christo ab inferis regresso populus fidelium congratulatur. David Ierusalem veniens a turbis cum cantu excipitur, et Christus ab Ierusalem coelos ascensurus ab angelis hymnologis laudibus suscipitur.