Reformed Theology sees prevenient grace as regeneration, as it concerns Soteriology.
Non Reformed Theology sees it more as freeing the will to be able to believe, but not necessarily regeneration. As I understand it, it's agreed that we are dead in sin, but God does something to us to enable us to believe, though the choice to believe is still ours to make.
I am more than willing to accept a better definition if someone would like to provide it. This is just my understanding as I've pieced it together through the years.
The question is, is this a biblical concept, and if so, what scripture would be used to support it?
It might be helpful to outline the 'ordo salutis' of Reformed vs non-reformed, to help make distinctions clearer.
Calvinist:
Election
Predestination
Calling
Regeneration
Faith
Repentance
Justification
Sanctification
Perseverance
Glorification
Arminian:
Calling
Prevenient Grace
Faith
Repentance
Regeneration
Justification
Perseverance
Glorification
Note, in the Calvinist scheme, regeneration precedes faith and repentance. In the Arminian scheme, it comes after faith and repentance.
Why is this important? Because regeneration means someone is given a new heart - in the Calvinist sense, they are given this new heart before actually coming to faith. Is that how the Bible puts it, though? That's the question.
I mention this because it highlights what prevenient grace is - the conviction of the Holy Spirit and the enablement to faith - the faith that leads to regeneration. In other words, in the Arminian scheme, it is still supernatural (not possible without the Holy Spirit) while conditioned on faith, not on predestination. God creates the right faith in the heart, but the person can still resist that faith.
It would be easy to pull up all the scriptures that condition salvation on faith. My point in all this is to show that if you believe the Holy Spirit prepares a person for salvation in any way, then you actually believe in prevenient grace. Election is a kind-of prevenient grace, it's just that the Calvinists don't call it prevenient grace, because 'prevenient grace' as a technical, theological term has come to mean 'resistable grace'. But in a broad sense, we all believe in prevenient grace of some kind.
This means that the only thing that should really get you to accept either the calvinist or arminian scheme, in this conversation at least, would come down to whether salvation is conditioned on faith, and if so, which of the above two orders of salvation come closer to what we see in the scriptures. I maintain that the Calvinist put regeneration in the wrong spot, and secondly that they are not following the main argument of the gospel as found in the scriptures that salvation is dependent on faith. Instead, they make salvation dependent on God's Hidden Will, his predestination, which not only short-circuits assurance of salvation but makes something of a confusion of faith itself.