"In this you greatly rejoice, even though now for a little while, if necessary, you have been distressed by various trials, so that the proof of your faith, being more precious than gold which is perishable, even though tested by fire, may be found to result in praise and glory and honor at the revelation of Jesus Christ" (I Peter 1:6-7).
These verses from First Peter seem to be a good place to start, as they state outright that the believer's faith is in a battle. Faith is being tested, tried, proven, and refined through the challenges of life. The trial of faith is the essence of the Christian battle. God wants to preserve faith, and Satan wants to destroy it.
Job was an incredibly righteous man, and he became a sort of test case for God and Satan. Satan's goal was for Job to reject faith ("curse You to Your face"), and Job's resolve was to maintain faith ("though He slay me, I will hope in Him"). Peter's battle was the same; Satan wanted to destroy faith ("sift you like wheat"), but Jesus prayed for preservation of faith ("that your faith may not fail").
Satan wages that same battle with every believer; each Christian faces the same challenge of maintaining faith in the midst of adversity. In essence, this is the most basic struggle of the Christian life. The question is whether a Christian will believe God even when he can't see God's truth displayed experientially or whether he will throw away God's words when life does not seem to work out. Faith is not faith when it insists on seeing to believe; faith clings to God's truth precisely when no evidence is seen.
As I studied through these verses, I was struck over and over again with how these verses look forward to an expected result, and they do so because they are founded on a concrete basis of truth. This is faith in action. I'm just going to highlight some key phrases to illustrate this principle.
The expected result of contentment and hope in Hebrews 13:5 are based on what " He Himself has said."
Faith looks expectantly for "God [to] supply all . . . needs" (Philippians 4:19).
Peter clung to God because He had "words of eternal life" (John 6:68).
The believer maintains faith by focusing on what transcends time and experience: "things which are not seen" and that "are eternal." Because of his faith, he expects something in the future: the "inner man is being renewed day by day" and "an eternal weight of glory" that he believes is being produced, though not yet fully achieved (II Corinthians 4:16-18).
The believer looks forward to see his tried and eventually victorious faith "result in praise and glory and honor at the revelation of Jesus Christ" (I Peter 1:6-7).
The Christian believes that "after you have suffered, . . . God . . . will Himself perfect, confirm, strengthen, and establish you" (I Peter 5:10).
James includes another verse that openly acknowledges "the testing of your faith," but it looks for the "perfect result" of "produc[ing] endurance" and of being "perfect and complete, lacking in nothing" (James 1:3-4).
Peter again reminds believers of the battle for faith, stating that they must "be of sober spirit, . . . on the alert." He warns of an "adversary" who is "seeking . . . to devour" (I Peter 5:8).
The believer equipped in God's armor and with fortified by faith expects to "be able to stand firm against the schemes of the devil" (Ephesians 6:10-11).
The battle for faith is one that demands "weapons," one of which is the "shield of faith . . . to extinguish all the flaming arrows of the evil one" (Ephesians 6:16). That the battle hinges on what one believes is evident due to the necessity of "taking every thought captive" (II Corinthians 10:4-5).
When Peter urges, "Humble yourselves under the mighty hand of God," (an evidence of faith in Him), he also expects the result "that He may exalt you at the proper time" (I Peter 5:6).
Faith asks God for wisdom, believing that "it will be given to him" (James 1:5).
Faith identifies true, honorable, right, pure, lovely, and well-reputed thoughts and evidences faith by choosing to "dwell on these things" (Philippians 4:8).
Faith does not "throw away [its] confidence," but looks forward to "when [one has] done the will of God," expecting the fulfillment of "what was promised" (Hebrews 10:35-36).
Even when the soul is "in despair," it determines to "hope in God," confident that it "shall again [have reason to] praise Him" (Psalm 42:5).
The soul that would despair except for believing it will again "see the goodness of the LORD" will in faith confidently "wait for the LORD" (Psalm 27:13-14).
Indeed, "God is faithful" and worthy of the believer's faith. God will not leave His children forever under the temptation, "but with the temptation will provide the way of escape also" (I Corinthians 10:13). The believer can have faith in that future expectation of God's fulfilled promise.
The Christian's battles are all about faith. If it is true, and I believe it is, that most discouragement is due to wrong thinking, then faith in God's truth is what is needed to win the battle. If discouragement, regardless of its cause, can be countered with right thinking, then it is completely logical that faith is indeed the key component in the fight. Granted, it is not always easy to believe. The awfulness of life might seem to be in stark contradiction to God's promises, but when a Christian chooses to believe God's truth and when he looks forward to the result that God has declared He will achieve, that believer can have victory over discouragement or any other battle.
"And this is the victory that has overcome the world -- our faith." I John 5:4 (NASB)