She also killed the Prophets of the Lord and together they did much evil in the sight of the Lord. Thus Jehu rooted Baal out of Israel. You have I revealed and committed my cause. Put on the whole armor of God, that ye may be able to stand against the wiles of the devil. For we wrestle not against flesh and blood, but against principalities, against powers, against rulers of the darkness of this world, against spiritual wickedness in high places.
Many people are confused about the difference between prayer and warfare.
The Strong's Concordance says that Prayer is made to God in intercession, supplication, worship, etc. In these scriptures, David is praying to the Lord. He is not doing warfare against the enemy. Prayer is an important part of our life and we need to pray often to the Lord and make our requests known unto Him. We also see in scripture that Jesus prayed.