Wherefore as the Holy Ghost saith, To day if ye will hear His voice…-Hebrews 3:7

(H)ow is it that men can hear the wooing of the cross of Calvary, and yet come not to Christ? How is it that when we preach about the sufferings of Jesus, and close up by saying, “yet there is room,”-how is it that when we dwell upon His cross and passion, men are not broken in their hearts? It is said,

“Law and terrors do but harden,
All the while they work alone:
But a sense of blood-bought pardon
Will dissolve a heart of stone.”

Methinks the tale of Calvary is enough to break a rock. Rocks did rend when they saw Jesus die. Methinks the tragedy of Golgotha is enough to make a flint gush with tears, and to make the most hardened wretch weep out his eyes in drops of penitential love; but yet we tell it to you, and repeat it oft, but who weeps over it? Who cares about it? Sirs, ye sit as unconcerned as if it did not signify you. Oh! behold and see all ye that pass by. Is it nothing to you that Jesus should die? Ye seem to say “It is nothing.” What is the reason? Because there is unbelief between you and the cross. If there were not that thick veil between you and the Saviour’s eyes, His looks of love would melt you. But unbelief is the sin which keeps the power of the gospel from working in the sinner: and it is not till the Holy Ghost strikes that unbelief out-it is not till the Holy Spirit rends away that infidelity and takes it altogether down, that we can find the sinner coming to put his trust in Jesus. ~ C.H. Spurgeon

http://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0003.cfm