Regardless, that doesn't make it pointless at all. God uses tools to carry out his will, including men. A Calvinist should be happy to evangelize and accomplish God's purpose. And whether or not Nineveh was predestined to be destroyed, if they were warned then they would be completely without excuse.
But I can't help but think that this statement is built on the 'T', and the verse Rom. 1:20. Of course the reason they are without excuse is that, even though fallen, they can discern right from wrong. The conscience either accusing or excusing. If they know right from wrong, then they can also volitionally choose. Well, not if you are a 1 point Calvinist that holds to the 'T'. In that case, no one can hear and respond to the gospel, even if the conscience affirms it. However, the NT paints a clear picture that 'rejection' of Christ is the issue, and that men will be held accountable for it. All have sinned, and Christ has died to settle the sin issue once and for all. Yet, one is sent to Hell for rejecting what the 1 point (T) says they are incapable of doing, that of being convinced Jesus is the Christ, the Son of God who died for their sins. And so, God passes by the reprobate, yet we are to evangelize with a message that demands they believe??
"you need to believe what you are incapable of believing!!" How could you be happy about that? If God has passed by some, then telling them to believe the Gospel is telling them to believe a lie. "For God so loved the world (the elect) that he gave (to the elect only) His only begotten son, that whoever (excluding the reprobate) believes (which is an implanted commodity) in Him shall not perish but have eternal life." How can one present John 3:16 if it is literally impossible for them to believe it?
Well there are Calvinists that don't believe in "double" predestination, that men are elected to die but rather only that some are elected.
R.C. Sproul would say, "Has not God chosen from eternity not to elect some people? If so, then we have an eternal choice of non-election which we call reprobation. The inference is clear and necessary, yet some shrink from drawing it." Basically he is saying you aren't willing to man up and call a spade a spade. If T, then U, then L, etc. etc.....double predestination.
I'm not really intereted in the implications that God is the author of evil, as I understand the arguments that refute this. Essentially that man is free to sin by his own volition, but incapable to respond by his own volition.
-“The Bible treated allegorically becomes putty in the hands of the exegete.” John Walvoord
"I'm not saying scientists don't overstate their results. They do. And it's understandable, too...If you spend years working toward a certain goal and make no progress, of course you are going to spin your results in a positive light." Ivellious