And that brings me to the point: are you really that sure that Calvinism is 100% correct? Any doctrine constructed by humans is likely to be flawed somehow. I know, I know, you say it wasn't constructed by humans, it was constructed by God. But we humans had to discover the doctrine from Scripture. And we see through the glass darkly, my friend.
It seems therefore worthwhile to live out the Great Commission under the assumption that we do not fully understand the nature of free will, predestination, and election.
A refreshing reminder of why Protestants had no missionary activity prior to 1800.