If the Calvinist position of election is true, preaching the Gospel is unnecessary, but the be must be some reason we a commanded to preach the Gospel to the world that has a real pupose. Whitefield's contention that it enables the elect to understand that he is part of that 'happy number' makes no logical sense.
It's called a command of the Lord, ctd. Whether it makes sense to us, or not, shouldn't matter, so long as we call Christ LORD. But if "reason" is your lord, and your own reasoning needs to understand the whole purpose before you'll obey the command, I suppose you have identified a real problem.
Notice that the article makes the following observations:
Under Whitefield's preaching the revival spread to Bristol and the West country in February and March 1739, and when he left that area at the beginning of April 1739, John Wesley was given the oversight of the work.Note that the revival work began with Whitefield. Also note that Whitefield was profoundly influenced by the great evangelists in the US...
he had, during 1740, made close friendships with such American evangelicals as the Tennents and Jonathan Edwards; through them he was doubtless led into a deeper understanding of Puritan theology and its relevance to evangelism and revivals. He also witnessed the outstanding blessing on their preaching.
Evangelism has always been a part of "orthodox" Calvinism. A failure to evangelize is often erroneously cited as a fault of Calvinism (as you point out above). A denial that evangelism is even neccesary is a defining trait of the perjorative "hyper Calvinism". Now, if we are not heeding our Lord's command to preach the gospel to, and make disciples of all nations, Calvinists indeed make themselves a woeful and reprehensible people for not following the words of our Lord.
(footnote) Before I posted this article, I was considering another article from albatrus.org to post - one that speaks more specifically to the question of Calvinism and evangelism. That article says this:
"this is the faith which has caused the Reformed Church in America to become one of the great missionary churches of all time. If you are conversant with the history of foreign missions, you know that, of course. You know that there are few churches, few denominations, which have sent forth so many to the mission fields of the world in proportion to their membership."I may still post it in the future, but for now you can read that other article here
Even if God did predetermine who would and would not be saved for not other reason than that is what He decided, there is no way for man to be able know if it is true.