"When a man is afraid of self examination, his fear is suspicious. He who does not dare to apply the plumbline to his wall may rest assured that it is out of perpendicular. A sincere man will pray, 'Lord, let me know the worst of my case.' It is far better to suffer needless distress than to be at ease in Zion, and then perish of the dry rot of self deceit." - Spurgeon's Sermon Notes
Recommended reading:
The Forgotten Spurgeon, by Iain Murray
A Defense of Calvinism - by Charles Spurgeon