You said:You clearly questioned obedience to the Great Commission. "What do I have to lose?" Obedience. As far as any person's salvation being at stake, I can't save anyone. But God uses means to reach the lost, and the primary means is the preaching of the Gospel. To not do so is open rebellion against God. So, I ask again, are you advocating disobedience to the Great Commission?
I am saying that the Great Commission is evidence for free will and that Calvinism is not entirely accurate. If we have no free will, the Great Commission is unnecessary. God can and will save His elect regardless of the Gospel being shared. People would hear the unavoidable call and flock by the thousands to church to hear the Gospel regardless of the Gospel being shared. Yet the Great Commission is there. Not because it is necessary, but because God honors us with privilege of sharing it.
So the question remains, if Calvinism is true, there is absolutely nothing that will prevent the predestined elect from hearing the Gospel and becoming saved. There is no need to worry about apostasy, because if they are truly elect, they would inevitably come crawling back.
So once again if Calvinism is true, what do we have to lose?