David of the bible seemed like he was constantly fighting the enemy. Be it the giant Philistines. Be it Saul. Be it the enemies of the state. Be it temptation. He was always in battle. One constant remained at his side. That was God and God working through people like Jonathan or Bathsheba. He could depend solely on God always. We today are constantly fighting the enemy as well. All the time. And as with David we have to rely solely on the Lord to get us through.
Thus says the Lord: “Cursed is the man who trusts in man and makes flesh his strength, whose heart turns away from the Lord. He is like a shrub in the desert, and shall not see any good come. He shall dwell in the parched places of the wilderness, in an uninhabited salt land. “Blessed is the man who trusts in the Lord, whose trust is the Lord. He is like a tree planted by water, that sends out its roots by the stream, and does not fear when heat comes, for its leaves remain green, and is not anxious in the year of drought, for it does not cease to bear fruit.” The heart is deceitful above all things, and desperately sick; who can understand it?