Unbelief is a foundational sin because it underlies many of the other sins we experience. Charles Spurgeon called unbelief, “. . . the parent of every other iniquity.” Steven Barabas wrote, “. . . the gravest sin of the Church is unbelief for it makes God to be a liar.” Unbelief was the reason why the Israelites failed to enter the promised land, it caused the Apostle Paul great sorrow, and it was a sin that Jesus sternly admonished. The writer of the book of Hebrews summarized the consequences that the fledgling nation of Israel faced because of unbelief:

Take care, brothers and sisters, that there will not be in any one of you an evil, unbelieving heart that falls away from the living God. (Hebrews 3:12)

Twelve spies entered the promised land – all of them gave a good report that it was a land flowing with milk and honey. Two of the spies believed the word of God – that God had promised them the land. Rather than believing the word of God, ten of the spies were fearful of the “giants” in the land. Our thoughts are influenced by where we focus our attention. The more we focus on our problems, the larger they seem; and conversely, the more we focus on God, the greater our confidence in God. The writer of Hebrews continued on:

But encourage one another every day, as long as it is still called “today,” so that none of you will be hardened by the deceitfulness of sin. For we have become partakers of Christ if we keep the beginning of our commitment firm until the end, “TODAY IF YOU HEAR HIS VOICE, DO NOT HARDEN YOUR HEARTS, AS WHEN THEY PROVOKED ME.” For who provoked Him when they had heard? Indeed, did not all those who came out of Egypt led by Moses? And with whom was He angry for forty years? Was it not with those who sinned, whose dead bodies fell in the wilderness? And to whom did He swear that they would not enter His rest, but to those who were disobedient? (Hebrews 3:13-18)

How were they disobedient? It was unbelief. Unbelief causes us to doubt the promises of God’s word. If we do not take God at His word, then we fail to appropriate His precious and magnificent promises. We not only fail to realize the blessings from His word, but we also miss the benefits that accrue to us from Jesus’ sacrifice on the cross. Jesus came that we might have life and have it more abundantly. Unbelief robs us of the abundant life because we doubt that promise applies to me. Our failure to believe His word is disobedience and consequently we do not enter into His rest.

The promised land is a picture of the life of peace and joy that is the birthright of God’s children. The normal Christian life is a life of consistent joy and peace in Christ – anything less than that is a subnormal life. The Israelites failed to enter the promised land and we fail to enter into joy and peace because of our unbelief:

And so we see that they were not able to enter because of unbelief. (Hebrews 3:19)

Some have called unbelief the greatest of all sins because people reject God’s promise of redemption through Jesus Christ. This is a matter of FAITH: For – All – I – Trust – Him.

Charles Spurgeon gave this earnest invitation to those in the throes of unbelief:

I think I see you in some place in Hell, tied to a rock, the vulture of remorse gnawing your heart, and up there is Lazarus in Abraham’s bosom. You lift up your eyes and you see who it is. “That is the poor man who lay on my dunghill and the dogs licked his sores. There he is in Heaven, while I am cast down. Lazarus—yes, it is Lazarus, and I who was rich in the world of time am here in hell. Father Abraham, send Lazarus that he may dip the tip of his finger in water, to cool my tongue.”

But no! it cannot be, it cannot be. And while you lie there, if there is one thing in Hell worse than another, it will be seeing the saints in Heaven. Oh, to think of seeing my mother in Heaven while I am cast out! Oh, sinner, only think, to see your brother in Heaven—he who was rocked in the selfsame cradle, and played beneath the same roof-tree—yet you are cast out.

And, husband, there is your wife in Heaven, and you are amongst the damned. And see you, father! your child is before the throne, and you! accursed of God and accursed of man, are in Hell. Oh, the Hell of Hells will be to see our friends in heaven and ourselves lost.

I beseech you, my hearers, by the death of Christ—by His agony and bloody sweat—by His cross and passion—by all that is holy—by all that is sacred in Heaven and earth—by all that is solemn in time or eternity—by all that is horrible in Hell or glorious in Heaven—by that awful thought, “forever”—I beseech you lay these things to heart, and remember that if you are damned, it will be unbelief that damns you. If you are lost, it will be because you believed not on Christ, and if you perish, this shall be the bitterest drop of gall—that you did not trust in the Savior.

The question is, “Will you take God at His word and trust Him for great and mighty things?” If you really believed that God meant what He said, then you would obey His word. As you step out in faith, you will see God work in ways you could have never imagined:

Let’s hold firmly to the confession of our hope without wavering, for He who promised is faithful. (Hebrews 10:23)