Power is a force that can be used for good or evil. Typically, power can be obtained from a position that is held or a relationship that entitles an individual to use another’s power. In an effort to obtain power, some are willing to kill or usurp the power that belongs to another. The easiest way to get power is to develop a relationship with someone that already has it, for instance a relationship with Jesus Christ entitles you to use the authority of his name to conquer the devil (Acts 4:7).
Joab, the commander of David’s army, had power because of the position he held and because of his relationship with David. After Absalom revolted against David, Joab killed Absalom even though David had commanded him not to. As a result, David replaced Joab as the captain of his host (2 Samuel 19:13). Because of the power he had as the commander of the Israelite army, Joab was able to retain his position in spite of David’s attempt to replace him. Joab did so by killing Amasa, the new commander (2 Samuel 20:10).
In this situation, it could be said that Joab had too much power. Although he worked for David, David was unable to fire him. At the root of the problem was the conspiracy between David and Joab to kill Uriah. When Uriah refused to have sex with his wife after being brought home from the battle field, David wrote a letter to Joab. “And he wrote in the letter, saying, Set ye Uriah in the forefront of the hottest battle, and retire ye from him, that he may be smitten, and die” (2 Samuel 11:15).
David used his power over Joab to force him to commit murder. Joab was merely following David’s command when he retreated and left Uriah to die. Therefore, his decision to kill Absalom was in a way a sign that he no longer trusted David’s judgement and he would decide for himself who should live or die by his sword.
Although it may have been better for Joab to follow his own conscience, he did not have the right to use the power of his position as commander of the army to undermine David’s authority. When Joab killed Amasa, he was attempting to come between David and the LORD, who was ultimately responsible for David’s actions, suggesting that David was not fit to be king. David’s position as king made him more powerful than Joab. David could have had Joab killed in order to remove him from his position, but he didn’t. David let Joab alone and didn’t attempt to replace him again.