J.C.Ryle reminds us of the fight that every Christian must fight, and fight daily. The fight against the world, the flesh and the devil:
The principal fight of the Christian is with the world, the flesh, and the devil. This is their never-dying foes. These are the three chief enemies against whom they must wage war. Unless they get the victory over these three, all other victories are useless and vain. If they had a nature like an angel, and were not a fallen creature, the warfare would not be so essential. But with a corrupt heart, a busy devil, and an ensnaring world, they must either fight or be lost.
The Christian must fight the flesh. Even after conversion they carry within them a nature prone to evil, and a heart weak and unstable as water. To keep that heart from going astray, there is need of a daily struggle and a daily wrestling in prayer. “I discipline my body,” cries Paul, “and bring it under subjection.” “I see a law in my members at war against the law of my mind, and bringing me into captivity.” “O wretched man that I am, who shall deliver me from this body of death?” “They that are Christ’s have crucified the flesh with its affections and lusts.” “Mortify your members which are upon the earth” (1 Cor. 9:27; Rom. 7:23, 24; Gal. 5:24; Col. 3:5).
The Christian must fight the world. The subtle influence of that mighty enemy must be daily resisted, and without a daily battle can never be overcome. The love of the world’s good things, the fear of the world’s laughter or blame, the secret desire to keep in with the world, the secret wish to do as others in the world do, and not to run into extremes—all these are spiritual foes which beset the Christian continually on their way to heaven, and must be conquered. “The friendship of the world is enmity with God: whosoever therefore will be a friend of the world, is the enemy of God.” “If any man love the world, the love of the Father is not in him.” “Whatsoever is born of God overcomes the world.” “Be not conformed to this world” (James 4:4; 1 John 2:15; 1 John 5:4; Rom. 12:2).
The Christian must fight the devil. That old enemy of mankind is not dead. Ever since the fall of Adam and Eve he has been going to and fro in the earth, and walking up and down in it, and striving to compass one great end—the ruin of a person’s soul. Never slumbering and never sleeping, he is always going about as a lion seeking whom he may devour. An unseen enemy, he is always near us, about our path and about our bed, and spying out all our ways. A murderer and a liar from the beginning, he labors night and day to cast us down to hell. Sometimes by leading into superstition, sometimes by suggesting infidelity, sometimes by one kind of tactics and sometimes by another, he is always carrying on a campaign against our souls. “Satan has desired to have you, that he may sift you as wheat.” This mighty adversary must be daily resisted if we wish to be saved. But “this kind does not come out” except by watching and praying, and putting on the whole armor of God. The strong man armed will never be kept out of our hearts without a daily battle. (Job 1:7; 1 Peter 5:8; John 8:44; Luke 22:31; Eph. 4:11).
Reader, perhaps you think these statements too strong. You fancy that I am going too far, and laying on the colors too thickly. You are secretly saying to yourself, that men and women may surely get to heaven without all this trouble and warfare and fighting. Remember the maxim of the wisest general that ever lived in England: “In time of war it is the worst mistake to underrate your enemy, and try to make a little war.” This Christian warfare is no light matter.