If you can sin and not weep over it, you are an heir of Hell. If you can go into sin, and afterwards feel satisfied to have done so, you are on the road to destruction. If there are no prickings of conscience, no inward torments, no bleeding wounds; if you have no throbs and heavings of a bosom that cannot rest; if your soul never feels filled with wormwood and gall when you know you have done evil, you are no child of God.
The Complete Works of C. H. Spurgeon, Volume 13: Sermons 728 to 787 (ed. 2015)