The inauguration of the kingdom in Christ's death, resurrection, ascension, and the outpouring of the Spirit directed believers' hopes toward a coming consummation of the kingdom, when the King now enthroned in heaven would return to earth as the rescuer of his people and the judge of all.
“Impossible” arrests our attention, abruptly opening a Greek sentence that runs for three verses. The author then builds suspense by withholding the detail of what, precisely, is “impossible” until the middle of verse 6: it is impossible, he finally says, “to restore . . . again to repentance” those who “have fallen away.”
In the book of Acts, Luke offers portraits of the life of the church in the aftermath of the Spirit's arrival. Luke elaborates on these four components in his later transitions showing that they are the means by which disciples who entered the church through baptism were taught "to observe all that I have commanded you," as Jesus had instructed.