Regeneration
The theory man fell from a sinless nature to one of depravity had to have a way to get man back to the ability to have faith. How could man be saved by faith without the ability to have faith. Wesley taught we could not have faith without regeneration.
John Wesley
In denying all natural free-will, and all power antecedent to grace
Inventions were devised to bridge the gaps theoretically, people like Wesley or even Augustine weren't bad people as much as people under pressure to make their doctrine fit. Yet, we shouldn't lie against truth just because someone points out our theory has short comings. So, maybe Wesley and others did have sinful whims.
Jas 3:14 But if ye have bitter envying and strife in your hearts, glory not, and lie not against the truth.
It seems clear to me that many men created theories that simply invented doctrine.
1Co 4:6 And these things, brethren, I have in a figure transferred to myself and to Apollos for your sakes; that ye might learn in us not to think of men above that which is written, that no one of you be puffed up for one against another.
As they invented the fallen nature theory others also invented the concept of regeneration. A doctrine designed to move man from his fallen state to the ability to have faith and have good works. When and how regeneration comes depends upon your denomination.
Catholic - baptismal regeneration,
Protestant - regeneration by the Holy Spirit before one can believe
Calvinist - regeneration in the womb in some cases.
All believe man needed help from a fallen state, or to remove the taint of original sin.
Catholics believe man fell into darkness (latin macula), they were graceless, so that with baptism the Holy Spirit grants grace to see and understand.
This is questionable because of New Testament adult baptism, for many understood the gospel before baptism. Their theory only works with a model of infant baptism and not adult baptism, who have faith prior. An example is the Ethiopian Eunuch who believed before baptism as did many others in the New Testament.
Joh 12:36 While ye have light, believe in the light, that ye may be the children of light.
The Apostles were not brought to understanding through baptism but through the visible life of Christ. The could believe before Christian baptism was exercised for the first time. Then others could believe through their word.
Joh 12:46 I am come a light into the world, that whosoever believeth on me should not abide in darkness.
and the scriptures were written for our belif, which would occur before life is granted to us, not before.
Joh 20:30 And many other signs truly did Jesus in the presence of his disciples, which are not written in this book:
Joh 20:31 But these are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name.
Thus instruction preceeds baptism and life, not after. Thus, infant baptism where life is theoretically granted before instruction does not fit.
Protestant regeneration is the belief God must regenerate the heart of man before God's word will penetrate it. This is from many Wesleyan and Baptist denominations. This supposedly occurs before baptism.
In regeneration, God changes our hearts. He gives us a new disposition, a new inclination. He plants a desire for Christ in our hearts. We can never trust Christ for our salvation unless we first desire Him. This is why we said earlier that regeneration precedes faith. [R. C. Sproul, Chosen by God, (Wheaton, IL: Tyndale Publishers, 1986), p. 118]
Though there are theories that use scripture to support God changing hearts directly, they actually fall apart with some examination.
1. God hardened Pharoh's heart.
God would only have to change his heart to a hardened state if he was born and lived in an unhardened state.
Thus the natural state of Pharoh was not hardened. It proves we can be born without hardness of heart.
2. God softened other's hearts.
It does not say how their hearts were softened or opened in some cases, perhaps by circumstances.
Act 16:14 And a certain woman named Lydia, a seller of purple, of the city of Thyatira, which worshipped God, heard us: whose heart the Lord opened, that she attended unto the things which were spoken of Paul.
In this case it wasn't Holy Spirit regeneration, it was the Lord that opened her heart, perhaps through gifts given to Paul. Perhaps through miracles. Perhaps as with the woman at the well, Jesus spoke of aspects of her life. We can only guess.
It wasn't regeneration as defined by protestants, it was an opening and not regeneration. It was by the Lord, not by the Holy Spirit.
We also know that God used natural emotions in bringing some to Christ.
Rom 11:11 I say then, Have they stumbled that they should fall? God forbid: but rather through their fall salvation is come unto the Gentiles, for to provoke them to jealousy.
God wasn't regenerating the heart but using psychology to influence. God worked in man's natural state to cause some to stumble and also to bring them back.
It wasn't regeneration but working with them as they were.
There were also statements in the prophets of giving Israel a new heart, but a verse preceding said they should give themselves a new heart.
Eze 18:31 Cast away from you all your transgressions, whereby ye have transgressed; and make you a new heart and a new spirit: for why will ye die, O house of Israel?
Man had to consent to the process.
Even with a new heart man must worship with all his heart, soul, mind, and strength. So with a new heart comes the necessary decision to do our best and use it all.
Since many incorrectly use Israel as an example of God opening the heart directly, taking them from stiff-necked to obedient, I need to throw in another passage.
God did not open the hearts directly but through fulfilled prophecy. He showed it beforehand so that he could change a stiff-necked people through fulfillment.
Isaiah 48
Isa 48:2 For they call themselves of the holy city, and stay themselves upon the God of Israel; The LORD of hosts is his name.
Isa 48:3 I have declared the former things from the beginning; and they went forth out of my mouth, and I shewed them; I did them suddenly, and they came to pass.
Isa 48:4 Because I knew that thou art obstinate, and thy neck is an iron sinew, and thy brow brass;
Isa 48:5 I have even from the beginning declared it to thee; before it came to pass I shewed it thee: lest thou shouldest say, Mine idol hath done them, and my graven image, and my molten image, hath commanded them.
Isa 48:6 Thou hast heard, see all this; and will not ye declare it? I have shewed thee new things from this time, even hidden things, and thou didst not know them.
Isa 48:7 They are created now, and not from the beginning; even before the day when thou heardest them not; lest thou shouldest say, Behold, I knew them.
Isa 48:8 Yea, thou heardest not; yea, thou knewest not; yea, from that time that thine ear was not opened: for I knew that thou wouldest deal very treacherously, and wast called a transgressor from the womb.
Isa 48:9 For my name's sake will I defer mine anger, and for my praise will I refrain for thee, that I cut thee not off.
Isa 48:10 Behold, I have refined thee, but not with silver; I have chosen thee in the furnace of affliction.
Isa 48:11 For mine own sake, even for mine own sake, will I do it: for how should my name be polluted? and I will not give my glory unto another.
Isa 48:12 Hearken unto me, O Jacob and Israel, my called; I am he; I am the first, I also am the last.