Apostle Paul dealt with believers warfare with the flesh in Gal 5:17 The desires of the flesh are against the Spirit, and the desires of the Spirit are against the flesh” Flesh here does not simply refer to the physical part of you. Paul does not regard the body as evil in itself. The flesh is the ego which feels an emptiness and uses the resources in its own power to try to fill it. Flesh is the “I” who tries to satisfy me with anything but God’s mercy.