With regard to Cornelius…
When someone is saved - we do not say that they are zapped in an instant. This is not the case. We know that general revelation through the creation (which was created by God’s spoken word - i.e. let there be light) shows us that there is a Creator and God. This is given in Romans 1 very explicitly…
Because that which may be known of God is manifest in them; for God hath shewed it unto them. For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: (Romans 1:19-20 KJV)
God “shewed”

it unto Cornelius and he responded…by seeking the one true God. Not a god that he made up in his mind…he was seeking after the one true God through what revelation that he had…It was the goodness of God that was leading him to repentance.
Or despisest thou the riches of his goodness and forbearance and longsuffering;
not knowing that the goodness of God leadeth thee to repentance? (Romans 2:4 KJV)
This is the type of drawing that God causes in a person. Why do we know that this was a special work that God was doing in Cornelius’ life? Because, we are told that there is no one that seeks after God (in truth)…
As it is written, There is none righteous, no, not one: There is none that understandeth,
there is none that seeketh after God. They are all gone out of the way, they are together become unprofitable; there is none that doeth good, no, not one. (Romans 3:10-12 KJV)
Therefore, any seeking of the truth - the One True God is completely of God. Many people are responding to general revelation but not in truth - they are sewing fig leaves and not looking for the coats of skins - seeking to clothe themselves with their own righteousness through manmade religion and pride…so any other seeking after another god is not of THE God.
So, this drawing does take place prior to repentance and regeneration…
However, when it comes to the reception of special revelation that accomapnies salvation (when the gospel comes in power and by revelation from the Father and witness of the Holy Spirit) you cannot ignore the scriptures that teach that only those who can come to Christ are given by the Father…
All that the Father **giveth me **shall come to me; and him that cometh to me I will in no wise cast out. (John 6:37 KJV)
No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day. (John 6:44 KJV)
And he said, Therefore said I unto you, that
no man can come unto me, except it were given unto him of my Father. (John 6:65 KJV)
And further…
As thou hast given him power over all flesh, that he should give
eternal life to as many as thou hast given him. (John 17:2 KJV)
Did he give everyone to Christ??? No He did not…but clearly, we are told that only those that the Father gives to Christ can come (AND BE JUSTIFIED)…those are the elect. And, at the proper time a preacher is sent, he preaches the gospel, it is heard, believed and then the sinner calls. The elect son/daughter comes to Christ - only the ones the He has foreknown can come and be justified…anyone else that is outwardly associated
has been caught up in the general call but receives no inward call from God and only those who receive this special inward call are justified…
Moreover whom he did predestinate, them he also called:
and whom he called, them he also justified: and whom he justified, them he also glorified. (Romans 8:30 KJV)
We do not find born again believers becoming unjustified in the Bible…we find them trimuphing!
We know that whosoever is born of God sinneth not; but he that is begotten of God keepeth himself, and that wicked one toucheth him not. (1 John 5:18 KJV)
No - a born again believer will not sin mortally…as 1 John 5:16 discusses…they overcome of the world (1John 5:4), they love, practice righteousness, keep the commandments, confess Christ, etc. This is a very loud message in 1John.
And while you might use other passages to try to show that one can become unjustified, you take them out of context and interpret them in such a way as to contradict other more clear passages of scripture - passages that you either pass over or twist so that they can no longer be recognizable.
C2C
desiringgod.org/ResourceLibrary/Sermons/ByDate/1985/514_Those_Whom_He_Predestined_He_Also_Called_Part_2/