‘Doubts and fears have power to spoil much of the happiness of a true believer in Christ. Uncertainty and suspense are bad enough in any condition — in the matter of our health, our property, our families, our affections, our earthly callings — but never so bad as in the affairs of our souls. And so long as a believer cannot get beyond ‘I hope’, and ‘I trust’, he manifestly feels a degree of uncertainty about his spiritual state. The very words imply as much. He says ‘I hope’, because he dares not say, ‘I know’.
Now assurance goes far to set a child of God free from this painful kind of bondage, and thus ministers mightily to his comfort. It enables him to feel that the great business of life is a settled business, the great debt a paid debt, the great disease a healed disease, and the great work a finished work; and all other business, diseases, debts, and works, are then by comparison small. In this way assurance makes him patient in tribulation, calm under bereavements, unmoved in sorrow, not afraid of evil tidings, in every condition content, for it gives him a FIXEDNESS of heart. It sweetens his bitter cups; it lessens the burden of his crosses; it smooths the rough places over which he travels; it lightens the valley of the shadow of death. It makes him always feel that he has something solid beneath his feet and something firm under his hands — a sure friend by the way, and a sure home at the end.’
J. C. Ryle, Holiness, p. 149