Blessed be the Lord my strength, which teacheth my hands to war, and my fingers to fight. (Ps. 144:1)
David learned warfare against the most brutal of opponents - wild animals. His task as a young man was the nurturing and protection of his father's sheep. Sheep are not pets. They are provision to those who possess them, and as such they are a form of wealth. David went out with his father's sheep not only to feed them, but to protect them. This was David's training ground!
In I Sam. 17:34, David says to Saul, "thy servant kept his father's sheep, and there came a lion, and a bear, and took a lamb out of the flock: And I went out after him, and smote him, and delivered it out of his mouth: and when he arose against me, I caught him by his beard, and smote him, and slew him. Thy servant slew both the lion and the bear."
We might want to rethink that image of Jesus as a meek and mild shepherd watching over peaceful flocks. Shepherds aren't punks.
David said moreover, The Lord that hath delivered me out of the paw of the lion and out of the paw of the bear, he will deliver me out of the hand of the Philistine.
David was a bold warrior because he knew the Lord was his deliverance. The Lord did not deliver him by shutting the lion's mouth (as he did for Daniel) but by giving David the strength to fight.
Then David said to the Philistine, Thou comest to me with a sword, and with a spear, and with a shield; but I come to thee in the name of the Lord of hosts, the God of the armies of Israel, whom thou hast defied.
David was not an indiscriminate warrior. He fought to protect, but he also fought because he was zealous for the Lord's Name. How dare this uncircumcised Philistine set himself against the Lord of hosts!
What strikes me most is, although God delivers through miracles, he also delivers through the strategic deployment of a carefully trained warrior. One who has been trained to war and will fight in the strength of the Lord. And so I thank the Lord for such bold and holy men of God!