Charles Spurgeon, known as the Prince of Preachers, obvious had much to say about preaching. This post brings together a number of the more powerful quotes.
While William Carey made his way overseas as a missionary he had an ally back home in England. That ally was the great baptist preacher, Andrew Fuller. Fuller stood firmly against those that claimed world missions unnecessary. His efforts helped pave the way for a great missionary movement.
Holding and promoting a Christian worldview is good and right, as Samuel James points out in this post; however, there is a right way for those with a Christian worldview to interact with those of different views. According to James, often Christians are failing to see the nuance of arguments and, in so doing, acting injudiciously.