Christ never failed to distinguish between doubt and unbelief. Doubt is can’t believe. Unbelief is won’t believe. Doubt is honesty. Unbelief is obstinacy. Doubt is looking for light. Unbelief is content with darkness.
Doubt is natural within faith. It comes because of our human weakness and frailty… Unbelief is the decision to live your life as if there is no God. It is a deliberate decision to reject Jesus Christ and all that he stands for. But doubt is something quite different. Doubt arises within the context the faith. It is a wistful longing to be sure of the things in which we trust. But it is not and need not be a problem.
When Doubt Becomes Unbelief, Tabletalk, 16, No.1, January 1992, p. 8-10.
Some of us who have preached the Word for years, and have been the means of working faith in others and of establishing them in the knowledge of the fundamental doctrines of the Bible, have nevertheless been the subjects of the most fearful and violent doubts as to the truth of the very gospel we have preached.
It seems to me that doubt is worse than trial. I had sooner suffer any affliction than be left to question the gospel or my own interest in it.
Doubt discovers difficulties which it never solves; it creates hesitancy, despondency, despair. Its progress is the decay of comfort, the death of peace. “Believe!” is the word which speaks life into a man, but doubt nails down his coffin.
I believe that the happiest of all Christians and the truest of Christians are those who never dare to doubt God, but take His Word simply as it stands, and believe it, and ask no questions, just feeling assured that if God has said it, it will be so.
Sermon, A Defense of Calvinism.
When the New Testament talks about doubt, whether you’re talking about the gospels or the epistles, it primarily focuses on believers. That’s very important. It’s as if you have to believe something before you can doubt it; you have to be committed to it before you begin to question it. So doubt is held up as the unique problem of the believer.
For some reason, we think of doubt and worry as “small” sins. But when a Christian displays unbelief…or an inability to cope with life, he is saying to the world, “My God cannot be trusted,” and that kind of disrespect makes one guilty of a fundamental error, the heinous sin of dishonoring God. That is no small sin.
The Ultimate Priority, Moody Press 1983, p. 140.
Doubts never send anyone to hell, but deception always does.
Doubting does not prove that a man has no faith, but only that his faith is small. And even when our faith is small, the Lord is ready to help us.
Commentary, Matthew 14.