"A spiritual experience which is thoroughly flavored with a deep and bitter sense of sin is of great value to him that hath it. It is terrible in the drinking, but it is most wholesome in the bowels, and in the whole of the afterlife. Possibly much of the flimsy piety of the day arises from the ease with which men reach to peace and joy in these evangelistic days. We would not judge modern converts, but we certainly prefer that form of spiritual exercise which leads the soul by the way of the weeping cross, and makes it its blackness before it assures it that it is 'clean every whit.' Too many think lightly of sin and therefore lightly of a Savior." - Spurgeon's Sermon Notes
Further recommended reading & listening:
The Best of The Daily Spurgeon
The Forgotten Spurgeon, by Iain Murray
A Defense of Calvinism - by Charles Spurgeon