Here's my problem with my Calvinist brothers who argue this way. In saying that Arminians need to come into communion with the real God they are saying Arminians are condemned until they repent of their doctrine because they aren't believing in the right God. So it is still our belief that saves us, and God's sovereignty is still denied.
I still believe I was saved and in communion with the real God before I knew what right doctrine was. I think most Calvinists who came away from Arminianism, if they were honest, would say the same.
Simply put, God saves. You aren't saved because you have correct doctrine. And you don't just get all the right doctrine the moment you are saved.
If Calvinist apologists would drop the seperation thing and treat Arminians as brothers, though mistaken, I think more progress could be made.
Now I know not all Calvinists see Arminians as lost, but it seems to be a major premise in the debates I see on these boards. Sad, really, to misuse grace to put ourselves above those who are where we just came from.