The following is paraphrased into modern English from Morning and Evening by Charles Spurgeon:
“For what the flesh desires is opposed to the Spirit, and what the Spirit desires is opposed to the flesh; for these are opposed to each other, to prevent you from doing what you want” (Galatians 5:17).
In every believer’s heart there is a constant struggle between the old nature and the new. The old nature is very active. It loses no opportunity to wield all the weapons of its deadly arsenal against new-born grace. Meanwhile, on the other hand, the new nature is ever on the watch to resist and destroy its enemy. Grace within us employs prayer, and faith, and hope, and love to cast out the evil. It takes to itself “the whole armour of God” (Eph 6:11) and wrestles earnestly.
These two opposing natures will never cease to struggle as long as we are in this world. The battle of “Christian” with “Apollyon” lasted three hours, but the battle of Christian with himself lasted all the way from the Wicket Gate to the river Jordan (see The Pilgrim’s Progress by John Bunyan).
The enemy is so securely entrenched within us that he can never be driven out as long as we are in this body. But even though we are closely assailed and often in sore conflict, we have an almighty Helper, even Jesus, the Captain of our salvation. He is ever with us. And he assures us that we will eventually come off more than conquerors through him. With such assistance the new-born nature is more than a match for its foes.
Are you fighting with the adversary today? Are Satan, the world, and the flesh all against you? Do not be discouraged or dismayed. Fight on! For God himself is with you: Jahveh-nissi is your Banner (see Ex 17:8–15), and Jahveh-rapha is your Healer (see Ex 15:25–26). Fear not, you shall overcome, for who can defeat Omnipotence? Fight on, keeping your eyes on Jesus (Heb 12:2), and though long and stern be the conflict, sweet will be the victory, and glorious the promised reward.
“From strength to strength go on;
wrestle, and fight, and pray,
tread all the powers of darkness down,
and win the well-fought day”
(Charles Wesley, from “Soldiers of Christ, Arise”)