Berakhot 4a states: "According to the order of the verse, upon being instructed by King David to go to war, the Sages first consulted with Ahitophel, then with the Sanhedrin, then they would ask the Urim and Tummim, and only thereafter was the general of the king’s army, Yoav, given the command to ready the military for battle."
David was God's prophet and King of Israelites. His decision about whether to go to war or not must be conclusive. But the text above tells Jews consulted others including Urim and Tummim. Shouldn't David's decision be conclusive and absolute? Why should they need to consult others when David made a decision? This all seems wrong to me.