This "good warfare" is carried on against three principal enemies—the flesh, the world, and the devil; and each of these enemies so closely allied to ourselves, and each so powerful and so hostile, that they must surely overcome us, unless we are "strengthened with might in the inner man."
There is the flesh, with all its baits, charms, and subtle attractions, continually laying its gins and traps for our feet, perpetually ensnaring us in some evil word or some evil work, and we in ourselves utterly defenceless against it. Said I defenceless? Yea, eager to run into it, like the silly bird that sees the grains of corn spread in the trap, but thinks not, when it flutters around it, that the brick will fall and confine it a prisoner. So we, allured by a few grains of corn spread before our eyes, often see not the snare, until we are fast entangled therein.
Faith then is that eye of the soul which sees the concealed hook; by faith we call upon the Lord to deliver us from snatching at the bait; and by faith, as a spiritual weapon, we cut at times the snare asunder. Oh, how defenceless are we, when the temptations and allurements of the flesh plead for indulgence, unless faith is in exercise, unless faith realises the hatred of God against sin, and brings into our consciences a sense of God's heart-searching eye, and his wrath against all transgression! But where the Lord has put this weapon of faith into the hand of his soldier, he will often strengthen his arm to wield it in these seasons of extremity, even though that weapon should cut and wound self.
How Joseph was enabled to resist the snares spread for his feet, by calling to mind the presence of the Lord! How he was strengthened to break asunder that bond which was fast twining round his heart, when faith sprang up in his soul, and he said, "How can I do this great wickedness, and sin against God?" How the three children who were about to be cast into the burning, fiery furnace, unless they would worship the golden image that Nebuchadnezzar had set up, overcame that dreadful temptation to renounce their God and prove apostates, by living faith!
Oh, what a weapon faith is, when the Lord does but give us power to wield it! How, as Hart says, it
"Cuts the way through hosts of devils,
While they fall before the word."
But when sin, temptation, and unbelief beat this weapon out of our hands, when it lies seemingly shivered at our feet, and we cannot get another such sword from God's armoury, how we stand naked and defenceless before our enemies! Therefore what need we have not merely of this heavenly grace in our souls, but to hold it fast and not let it go, lest the enchantress should catch our feet in her wiles and snares.
So, again, when Satan comes in with his fierce temptations and fiery darts, what but faith can enable the soul to stand up against them, as the Apostle says, "Above all, taking the shield of faith, wherewith ye shall be able to quench all the fiery darts of the wicked." Nothing but faith in God, in his power and presence; nothing but faith in Jesus, in his blood and his righteousness; nothing but faith in the holy Ghost, as lifting up a standard in the heart by means of his divine operations; nothing but faith in a triune God can enable the soul to battle against Satan's assaults.
Therefore see how indispensable faith is to fight a good fight, yea, so indispensable that a good fight is called emphatically "the fight of faith:" "fight the good fight of faith," implying that true faith will enable a man to come off more than conqueror through every battle and to survive every conflict.