I think that God does give what is needed to believe in Him and the salvation message....but each has those appointed times where they are presented with a choice which in many cases is over a period of time. He “draws” us to himself which indicates time... a progression of understanding and our willingness to hear or not.
Some will require years....some early on have a foundation of Christianity. But each man eventually chooses. The ability to turn away from the truth is evidenced in the scriptures. Also indicating a choice.
I agree with you that God draws us, but I disagree that once we are His we can walk away.
John 10:28 And I give them eternal life, and they shall never perish; neither shall anyone snatch them out of My hand.
I think the ones who we believe were one of us and walked away were never really one of us.