What did the Teacher mean when he said "He who endures to the end is the one who will be saved?" End of what?

Right, there will be no restart;
"And he cried out with a strong voice, saying: “She has fallen! Babylon the Great has fallen, and she has become a dwelling place of demons and a lurking place of every unclean exhalation and a lurking place of every unclean and hated bird! 3 For because of the wine of the anger of her fornication all the nations have fallen [victim], and the kings of the earth committed fornication with her, and the traveling merchants of the earth became rich due to the power of her shameless luxury.”
4 And I heard another voice out of heaven say: “Get out of her, my people, if YOU do not want to share with her in her sins, and if YOU do not want to receive part of her plagues. 5 For her sins have massed together clear up to heaven, and God has called her acts of injustice to mind. 6 Render to her even as she herself rendered, and do to her twice as much, yes, twice the number of the things she did; in the cup in which she put a mixture put twice as much of the mixture for her. 7 To the extent that she glorified herself and lived in shameless luxury, to that extent give her torment and mourning. For in her heart she keeps saying, ‘I sit a queen, and I am no widow, and I shall never see mourning.’ 8 That is why in one day her plagues will come, death and mourning and famine, and she will be completely burned with fire, because Jehovah God, who judged her, is strong." Rv18:2

Quoting the Whore of Babylon's distorted dogma book is not only useless but quite ironic.