So, do you believe that God changed from old to new in the area of 'regeneration'? Is the 'birth from above' a 'new' thing not previously done under the old covenant? Was Christ implementing something 'new' when He declared 'it behoveth you to be born from above', or was He revealing a mystery from of 'old', something that had always been?
I'm not sure what you mean with "God changed from old to new"
No, God didn't change, and never does. But He has not always interacted with man in the same ways throughout history. There was a time when the Spirit had not been poured out on all flesh, but that doesn't mean that God changed.
Regeneration, in the minds of [most] Reformers, is the aim of OT passages such as Jeremiah 31:31-34 and Ezekiel 11:19, 26:24-48
Jeremiah said explicitly that it would be a new covenant. This is expounded in Jeremiah as a new heart, new spirit.
When you get to Hebrews 9-10, it is clear that the new covenant was in stark contrast with the old. The blood of bulls and goats could never take away (or remove) sins. The clear implication is that the new covenant of a new heart and new spirit is exactly a removal of sins. Not simply a change of disposition, but a bona fide righteousness that exceeds justification.
New creation. Born from above. Partakers of the divine nature. Sinless inner man, in stark contrast with the sinful flesh.
The question then becomes - if God regenerates a man as the first act of grace, then He removes a man's sins and recreates his spirit in a sinless fashion first.
How on earth could justification appeal to a sinless man?
Why would a man rejoice in being "credited" with righteousness after one is already "recreated" righteous? It just doesn't jibe.
But one of the biggest issues is that this supposed first act of regeneration is a change of "want to" whereby a man now is willing to choose Christ. Choose what about Christ?
By all scriptural indications, he gospel is simply a promise to be believed, or a God to believe in, hope in, trust.
Scripture also makes it clear that it does not depend on the man who wills, or runs, but God. But the Calvinist view is that God gives man a change of disposition in order to choose. It's still counter to scripture, because it still has man choosing.
Whether a man is regenerate or depraved, it is not humanly possible to choose to believe a promise. It takes a the drawing, convicting and enlightening of the mind, by the Holy Spirit.
'New man' vs. 'old man' (long before Calvinism):
For the flesh lusteth against the Spirit, and the Spirit against the flesh; for these are contrary the one to the other; that ye may not do the things that ye would. Gal 5:17
For I delight in the law of God after the inward man: but I see a different law in my members, warring against the law of my mind, and bringing me into captivity under the law of sin which is in my members. Ro 7:22,23
I agree with what Paul wrote. In Galatians, however, I see no warrant for translations to capitalize "spirit"
It is the man's spirit warring against his own flesh. That should be evident from Paul's use of "inner man" in Rom 7
This happens after a person's spirit has been washed and recreated.
Most believers don't like this "sinless" line of thought. But we know that nothing unclean will ever enter the Holy City. SO our sins MUST be removed before we can enter.
The flesh will be made sinless "in the regeneration" (Matt 19:28)
When does our spirit become washed and cleansed from sin? Westminster has it happening upon death.
But that flatly denounces the substance of regeneration if regeneration happens as a first act of grace. It most certainly is not the last act of grace
