I found this a way better:
Paragraph 6:
"Some may have had a rather sudden realization of their calling, while others experienced a more gradual realization."
Paragraph 9:
"Simply put, by means of his holy spirit, God makes it clear to that person that he is invited to become a future heir in the Kingdom arrangement."
Paragraph 15:
"In fact, if you are wondering whether you have received the heavenly calling, that would in itself indicate that you have not received it."
God make it so clear that they do not have to think about if they are choosen but some of them need time to realize that they are choosen. Make absolut overlapping sense...