In the third aliyah, the first four lines complete the promise of blessings of the last few aliyot, but then the aliyah talks about severe, terrifying punishments if the Jewish people reject G-d's chukos (statutes) and mishpatim (ordinances) and if we don't do His mitzvahs. Rashi counts seven transgressions corresponding to seven punishments. The seven progressive transgressions are: failure to study Torah, failure to do the commandments, rejecting others that do the commandments, hating the sages, preventing others from observing, denying the divine origin of the commandments, denying the existence of G-d. Rashi says that each of these sins leads to the next.
The punishments described here include terrible famine and exile. The Torah says that our land will lie in desolation and finally will be paid its rest that it didn't have when we didn't keep the Sabbath of the land.
But the aliyah ends with G-d's promise that He will remember us in the land of our enemies, and not break his covenant by destroying us utterly.
