Faith believes the word of God, but unbelief questions the certainty of it (Psa. 106:24).
Faith believes the word, because it is true; but unbelief doubts thereof, because it is true (1 Tim. 4:3; John 8:45). Faith sees more in a promise of God to help, than in all other things to hinder; but unbelief, notwithstanding God's promise says, "How can these things be?" (Rom. 4:19-21; 2 Kings 7:2; John 3:11-12). Faith will make you see love in the heat of Christ, when with His mouth He gives reproofs, but unbelief will imagine wrath in His heart, when with His mouth and word He says that He loves us( Matt. 15:22-29; 25:34).
Faith will help the soul to wait, though God defers to give; but unbelief will take offense and throw up all, if God makes any tarrying (Ps. 25:5; Isa. 8:17; 2 Kings 6:33). Faith will give comfort in the midst of fears; but unbelief causes fears in the midst of comforts (2 Chron. 20:20, 21; Matt. 8:26; Luke 24:25). Faith will suck sweetness out of God's rod; but unbelief can find no comfort in His great mercies (Ps. 23; Num. 12). Faith makes great burdens light, but unbelief makes light ones intolerably heavy (Mal. 1:12, 13). Faith helps us when we are down; but unbelief throws us down when we are up (Micah 7:8-10; Heb. 4:11). Faith brings us near to God when we are far from Him; but unbelief puts us far from God when we are near to Him (Heb. 10:22; 3:12-13).
Where faith reigns, it declares us to be the friends of God; but where unbelief reigns, it declares us to be His enemies (Heb. 3:18; Rev. 21:8). Faith puts a man under grace; but unbelief holds him under wrath (Rom. 3:24-26; Eph. 2:8; John 3:36; 1 John 5:10; Heb. 3:17; Mark 16:16; John 8:24). Faith purifies the heart; but unbelief keeps it polluted and impure (Acts 15:9; Titus 1:15, 16). By faith the righteousness of Christ is imputed to us; but unbelief shuts us up under the law to perish (Rom. 4:23, 24; 11:32; Gal. 3:23).
Faith makes our work acceptable to God through Christ; but whatsoever is of unbelief is sin. For without faith it is impossible to please Him (Heb. 11:4; Rom. 14:23; Heb. 11:6). Faith gives us peace and comforts our souls; but unbelief works trouble and tossings, like the restless waves of the sea (Rom. 5:1; James 1:6).
Faith makes us see preciousness in Christ, but unbelief sees no form, beauty, or comeliness in Him (1 Pet. 2; Isa. 53:1-3). By faith we have our life in Christ's fullness; but by unbelief we starve and pine away (Gal. 2:20). Faith gives us the victory over the law, sin, death, the devil, and all evils; but unbelief lays us obnoxious to them all (1 John 5:4; Luke 12:46).
Faith will show us more excellency in the things not seen, than in them that are; but unbelief sees more in the things that are, than in things that will be hereafter (2 Cor. 4:18; Heb. 11:24-27; 1 Cor. 15:32). Faith makes the ways of God pleasant and admirable; but unbelief makes them heavy and hard (Gal. 4:6; 2 Cor. 12:10, 11; John 6:60; Psa. 2:3).
By faith Abraham, Isaac and Jacob possessed the land of promise, but because of unbelief, neither Aaron, nor Moses, nor Miriam could get either (Heb. 11:9; 3:19). By faith the children of Israel passed through the Red Sea; but by unbelief the generality of them perished in the wilderness (Heb. 11:29; Jude 5). By faith Gideon did more with 300 men, and a few empty pitchers, than all the twelve tribes could do, because they believed not (unbelief) God (Judges. 7:16-22; Num. 14:11, 14). By faith Peter walked on the water; but by unbelief he began to sink (Matt. 14:22-33) (Excerpted from John Bunyan, The White Devil).
But the Scripture has shut up everyone under sin, so that the promise by faith in Jesus Christ might be given to those who believe