The battle in our spiritual lives involves our minds being renewed. If we are walking in faith, filled with the Holy Spirit our minds take on a vital new role. Putting on the mind of Christ and renewing our minds prepares us not only to be a good witness, but to discern the will of God. Not having the mind of Christ or renewing our minds leaves us in the natural mind, relying upon our own understanding. And that does us more spiritual harm than good.