There are many out there that look at the way the Doctrines of Grace and Election are explained by John Calvin (ie.: a Calvinist position) and state that this view cancels any desire for missionary work.
I look at it this way: God knows where His sheep are located. He has graciously invited us to take part in a "scavenger hunt". If we do not join in, He will NOT leave one of His flock lost, someone else invited will be sent after them.
But how sorrowful will be that day when you Stand before Him and if you even have the strength to speak, have only this to say: "Even though the invitation came from the Creator of All, my time was more important for my tasks than to take part in some "silly scavenger hunt"."