"And when they saw him, they worshipped him: but some doubted" (Matt. 28:17).
Is doubt a sin? Not always. We should not, to begin with, say that doubt is the proper state for any mind; for if things were right, belief in the great spiritual realities would be as natural as seeing the light: therefore doubt is unnatural, something that should not be, and from which we ought to seek escape.
But doubt may be called at first a temptation rather than a sin--a temptation ready to recur from outward events and inward states of mind, and infections of thought from other spirits. These are not necessarily sinful. it is wrong not to seek deliverance from doubt--it is wrong to cherish it as an excuse for sin, to inquire captiously, to press frivolous objections, to seek evidence which is impossible or which we do not require in similar cases for practical action in life, to scatter doubt where we have no hope or wish for a solution of our own, and it is wrong not to feel for ever the pressure and misery of it.