Sinners are not saved through spontaneous regeneration. The means of salvation is the preaching of the Gospel. .
Brother Reformed,
We read faith itself is a "fruit" of the Spirit in Galatians 5:22, the tree that produces the fruit must exist before the fruit is grown, thus one must first have the Holy Spirit before they can have faith in the gospel. Also, life always precedes action, a dead person cannot do anything, therefore one must be first made alive (quickened) by the Holy Spirit before they can have faith in the gospel as sinners are said to be "dead in trespasses and sins" prior to becoming born again. In gospel regeneration, spiritually dead people are doing spiritual things such as believing, this is an impossibility, "Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be." (Romans 8:7)
The Holy Spirit uses the Gospel to convict sinners of their sinfulness and to provide them the hope found only in Christ. If this was not the role of the Holy Spirit, then how could anyone be saved? .
I agree on the purpose of the Holy Spirit, but disagree on the purpose of the gospel. You have regeneration and conversion as synonyms which they are not, the former always precedes the latter. The bible makes clear the purpose of the gospel, " who hath abolished death, and hath brought life and immortality to light through the gospel" (2 Timothy 1:10). If something brings something "to light", whatever was bought "to light" (in this case life and immortality) was already there. The gospel tells one how they were saved (through sovereign quickening of the Holy Spirit and the dead of Christ alone), it does not get them saved.
Jesus compares being born again to not being able to how men are unable to detect where the wind comes and goes from, "The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit" (John 3:8), but Jesus's analogy would fail if gospel regeneration were the truth because then one could indeed say, "this is the exact time the Holy Spirit entered me", so how then could it be similar to the wind in not being able to tell from where it comes and goes?
In Acts 10:43 Peter says to Cornelius, "Of Him all the prophets bear witness that through His name everyone who believes in Him receives forgiveness of sins.” Once again we see the Gospel being proclaimed to unbelievers; this in a a letter written to a believer. I can cite numerous other scenes just within Acts, but I believe I have made my point.
I would argue Cornelius does not prove your point, it proves mine that regeneration precedes faith in the gospel. He was born again before the preacher Peter even arrived.
First, notice that before he met Peter or heard the gospel, Cornelius "feared God with all his house" (Acts 10:2). And from the Bible we know that those who fear the Lord possess God's salvation (Psalm 85:9). Unsaved men do not fear God (Romans 3:18; Psalm 36:1)).
Second, see that Cornelius' prayers were "come up for a memorial before God" (Acts 10:4), before he heard or believed the gospel through Peter. And Proverbs 15:29( teaches us plainly that God only hears the prayers of the righteous.
Third, observe that Peter acknowledged in verses (Acts 10:34-35) that God had already accepted Cornelius before Peter ever met him.
"Then Peter opened his mouth, and said, Of a truth I perceive that God is no respecter of persons: But in every nation he that feareth him, and worketh righteousness, is accepted with him."
God bless,
Brother Joe