"You are halting between two opinions. You are sometimes seriously inclined, and at another time worldly gaiety calls you away. What little progress you do make in religion is but a limp. You have a little strength, but that is so little that you make but painful progress. Ah, limping brother, to you also is the word of this salvation sent. Though you halt between two opinions, the Master sends me to you with this message: 'How long halt ye between two opinions? if God be God, serve him; if Baal be God, serve him.' Consider thy ways; set thine house in order, for thou shalt die and not live. Because I will do this, prepare to meet thy God, O Israel! Halt no longer, but decide for God and his truth." - From Spurgeon's sermon Compel Them To Come In
Further recommended reading & listening:
The Best of The Daily Spurgeon
The Forgotten Spurgeon, by Iain Murray
A Defense of Calvinism - by Charles Spurgeon