When it seems like our prayers aren’t being answered

We do not need to fear the enemy, including when he seems relentless and our defense doesn't seem to be working. Truthfully speaking, the enemy lost at the cross. He lost the war, but he doesn't like to give up in the battle. How much more should we, who won the war in Christ, not give up in the battle? Why do we say, "Oh well. Jesus won the war, so who cares if we lose this battle?"