“Beloved friends, let us never look upon our own unbelief as an excusable infirmity, but let us always regard it as a sin, and as a great sin, too. Whatever excuse you may at any time make for others—and I pray you to make excuses for them whenever you can rightly do so—never make any for yourself. In that case, be swift to condemn. It is a very easy thing for us to get into a desponding state of heart, and to mistrust the promises and faithfulness of God, and yet, all the while, to look upon ourselves as the subjects of a disease which we cannot help, and even to claim pity at the hands of our fellow-men, and to think that they should condole with us, and try to cheer us.
It will be far wiser for each one of us to feel, ‘This unbelief of mine is a great wrong in the sight of God. He has never given me any occasion for it, and I am doing him a cruel injustice by thus doubting him. I must not idly sit down, and say, This has come upon me like a fever, or a paralysis, which I cannot help; but I must rather say, This is a great sin, in which I must no longer indulge; but I must confess my unbelief, with shame and self-abasement, to think that there should be in me this evil heart of unbelief.’”
—Charles Spurgeon, “Unbelievers Upbraided” (a sermon on Mark 16:14)