Well how did you know you needed a Savior?
Conviction of SIN, and of Judgement by the Holy Spirit does that for you.
The FIRST TIME that happened for me was back in the '50s as the result of "The Hour of Decision" radio show. Graham gave the invitation, and Beverley shea did "Just as I am", and I KNEW that I needed to be saved, but didn't really know what to do, so I did nothing, and the Conviction passed after a while. I made it a POINT NOT to be around when the "Hour of decision" after that. "Conviction of SIN" isn't pleasant, so I avoided things that might cause it.
But in '63, after a nervous breakdown, suicidal tendencies, and a hopeless future, in Houston (where I'd gone to escape my situation, but brought the problem along since it was me) the fellow I shared an apartment with got saved, and just the look of peace and joy on his face brought CONVICTION back. I KNEW I had to have that, or I'd die.
Since he was saved as a result of "Southern Baptist" outreach, Calvinist "Regeneration theology" never came up. ALL WE KNEW was "Conviction of SIN" by the Holy Spirit, Jesus and his Sacrifice being the Answer, and the need to Surrender and Repent. And of course that was enough.
Being "Born Again" isn't "Theological", it's a PERSONAL INTERACTION between the person under conviction, and God by the Holy SPirit. I cried out (literally) for Him to SAVE ME - and He did. That's when everything changed. THEN, of course, I started to learn what it was all about starting with going through the Bible for the first time in many years.
Only convicted sinners who are regenerated by the Spirit know they plight before a Holy God,
Actually "Conviction of SIN, and of Judgement by the Holy Spirit does all that nicely. I don't know about any "Previous regeneration" process.
why did God do all of this to begin with Bob?
Simple!!! I (along with everybody else who SINNED) was LOST IN SIN, and Jesus came and died as the SIN OFFERING that cleanses from SIN. So now IN HIM, I'm perfect before God with Jesus' perfection (which is the only "perfection" I'll ever have on earth.
If you do not believe the fall affected the whole person, faculties and all, heart, mind, soul. Then why do people even need to be saved anyway?
Because, just like ADAM BEFORE THE "FALL", we let our Personal strong desires (Lusts) CONCEIVE, and become SINFUL ACTIONS, resulting in our falling short of God's Glory.
You apparently need Adam's HUMAN NATURE to "Change", to support your "Theology", but it didn't. After he SINNED, he became a "Sinner" just like the rest of us. Did YOUR "Human Nature change, after you sinned the first time???
When he was PERFECT (without your so called "Sin nature"), He fell into sin, so nothing in him changed at all. He acted in keeping with His HUMAN NATURE, just like you and I, and, as he was WARNED, he DIED spiritually on the spot (just like we all do when we first SIN), but remained physically alive for many years afterwards..
No argument about Adam's "Environment" changing (since the earth was CURSED for his sake).