"A lady, who heard Whitefield, in Scotland, preach upon the words, 'And the door was shut,' being placed near two dashing young men, but at a considerable distance from the pulpit, witnessed their mirth; and overheard one say, 'Well, what if the door be shut? Another will open.' Thus they turned off the solemnity of the text.Mr. Whitefield had not progressed far when he said, 'It is possible there may be some careless, trifling person here today, who may ward off the force of this important subject by lightly thinking, 'What matter if the door be shut? Another will open.' The two young men were parallelized, and looked at each other. Mr Whitefield proceeded: 'Yes, another will open. And I will tell you what door it will be: It will be the door to the bottomless pit, the door of hell! The door which conceals from the eyes of angels the horrors of damnation!'" - 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