He is asaying that when the true Gospel is preached/taught, the end result is that sinners will be saved by the calvinistic framework of understanding, but that salvation itself does NOR hinge on us accepting/or even understanding that framework!
To give context to the statement, and perhaps correct Winman’s misunderstanding of what is being said:
"I have my own private opinion that there is no such thing as preaching Christ and Him crucified, unless we preach what nowadays is called Calvinism. It is a nickname to call it Calvinism; Calvinism is the gospel, and nothing else."
“There is no soul living who holds more firmly to the doctrines of grace than I do, and if any man asks me whether I am ashamed to be called a Calvinist, I answer—I wish to be called nothing but a Christian; but if you ask me, do I hold the doctrinal views which were held by John Calvin, I reply, I do in the main hold them, and rejoice to avow it. But far be it from me even to imagine that Zion contains none but Calvinistic Christians within her walls, or that there are none saved who do not hold our views. Most atrocious things have been spoken about the character and spiritual condition of John Wesley, the modern prince of Arminians. I can only say concerning him that, while I detest many of the doctrines which he preached, yet for the man himself I have a reverence second to no Wesleyan; and if there were wanted two apostles to be added to the number of the twelve, I do not believe that there could be found two men more fit to be so added than George Whitefield and John Wesley. The character of John Wesley stands beyond all imputation for self-sacrifice, zeal, holiness, and communion with God; he lived far above the ordinary level of common Christians, and was one "of whom the world was not worthy." I believe there are multitudes of men who cannot see these truths, or, at least, cannot see them in the way in which we put them, who nevertheless have received Christ as their Saviour, and are as dear to the heart of the God of grace as the soundest Calvinist in or out of Heaven.” (http://www.spurgeon.org/calvinis.htm)