I don't like to jump into someone elses turf but you asked one of the most annoying questions that plagued me for years. It wasn't until I embraced a Reform position that I understood them.
There are two such people who were clearly regenerated (or saved) before they were born; Jeremiah and John the Baptist. (We could go into others but the references are vague.)
Please consider the following verses:
Luke 1:13-15: "But the angel said to him: "Do not be afraid, Zechariah; your prayer has been heard. Your wife Elizabeth will bear you a son, and you are to give him the name John. He will be a joy and delight to you, and many will rejoice because of his birth, for he will be great in the sight of the Lord. He is never to take wine or other fermented drink, and he will be filled with the Holy Spirit even from birth."
and
Jeremiah 1:4-5 "The word of the LORD came to me, saying, "Before I formed you in the womb I knew you, before you were born I set you apart; I appointed you as a prophet to the nations."
Now, can you explain to me that if one needs to make a "profession of faith" why these two were saved before they were born? No one has yet.
Your TULIPs are all connected, in a bizarre circular way.
Since you don't believe it possible for someone to reject salvation and you equate it with receiving the Spirit, you lead yourself to these questions.
John the Baptist was indeed filled with the Holy Spirit prior to birth. But guess what? Every little baptised baby is likewise filled with the Spirit of God.
We still have lives to lead and choices to make that can affect our destination.
Of course, if you want ot believe that God thrusts His Spirit into those He chooses and that they are then guaranteed salvation and have no choice in the matter, that is your choice. But we don't share all of your assumptions.
SD