Hi truth,
In a couple of his Bible studies (Foundational Truths and Despising the Word of God), Ray talked about such people who deny these truths. The tactic he advised is to take control by going on the offensive: rather than try and explain all these truths, make THEM give a verse that says what THEY think is the truth. In this case, make THEM show you a verse that says "God sometimes is willing that some will perish."
Or with 1 Tim. 2:4, "God wills that all mankind be saved..." If they deny this, make THEM show you a verse that says "God does NOT will that all mankind be saved...."
The point being, they cannot come up with a verse that says the opposite of these truths, and if they did, the Bible would contradict itself and we would have to throw it out anyway. Sure, they will try--you ask them to show you a verse that says "God is willing that some will perish" and they will say "He says 'Depart from me, I never knew you'" or something like that. They will think they are coming up with a good answer, because they are quoting the Bible. But that verse--nor any of the "everlasting punishment" verses--does not say that God is willing that some perish, or that God does NOT will that all mankind be saved. They think it means that, but they lack understanding.
Of course, this tactic will rarely work, and I wouldn't recommend using it with most Christians. If they are genuinely interested and want to learn the truth, by all means. But if they just want to point out where you are wrong, it's a fruitless endeavor. God has blinded them, and only God can open their eyes, no matter how much sense you talk to them.