Hey Martin.Hello Dave.....,
I don't have much time right now, but I will just say that, in common with many of the Puritans (Most notably William Perkins), I do not see regeneration as a one-off event, but rather as a process. I think it is clear that God must open the heart of someone before he can repent and believe, but also that regeneration is not definitely over until after he has done both those things. I wrote a series of articles about 15 years ago on the New Birth. Here is the relevant one: New Birth (7) The Order of the New Birth Have a browse.
Most Calvinists see two choices, born again or the flesh. That's the biggest error right there. OT believers could not be born again, yet they believed. Even Calvin recognized this, but, I believe he started with the wrong framework foundationally. He recognized that there was a difference in regeneration from the OT to the NT, but framed it with the assumption that OT believers must have been born again, and thus regenerate, and that what happened in the NT must be something more. Half of that is true. What happened in the NT WAS something more, but that 'more' was being born again. Foundationally, the OT believers could not be born again.
Calvin assumed OT believers must have been born again, how else could they believe? He reasoned. That assumption is based off of a faulty understanding of Scripture, mainly idea total depravity and ignoring the historical context that I spoke about earlier.
Ultimately Calvinism minimizes God and elevates man.
In the Bible when God acts this is based on His own nature which is proclaimed. Sometimes God acts for a specific purpose and so that all do not respond He hardens their hearts (like with Pharoah - God's actions are no so benign that they do not draw men, so God hardened Pharoah's heart to accomplish His plan).
Did you mean to say Arminianism minimizes God and elevates man?