The Jews are an enigmatic people. We are not a religion, for there are many who would say they are Jewish but are not religious; we are not a nation, a nation is identified by its land and Jews have not had a land for most of their history; and we are not a culture or race because we do not look alike or share cultural markers such as dress, food, and spoken languages.
I believe Jews are primarily a family. People can be born into Judaism or join it, just as they can be adopted into a family. They can try and leave a family but would never the less still be considered a part of it, just as in Judaism. One can violate the rules of the family but are still considered part of it, just as with Judaism.
The beginning of this Torah portion prepares the Jewish people to enter the land as a nation. It opens with a unique national ceremony of blessings and curses which involved the entire nation and must be performed when the Jews first enter the land on Mount Gerizim and Mount Aval.
Though the beginning of the portion outlines the Jewish people as a nation in a land, it ends with a description of the holidays and their function facilitating the Jews as a big family. We are told three times a year to gather in the Temple, a big house, we must bring tithes of food with us just to eat there. Three times a year the Jews converge at the big house to eat their meals together, like a big family.
Perhaps the lesson is that, as the Torah ends and the people come to be a nation within a land living on the global stage, it must also function as a big family with feelings of familial responsibility, intimacy and concern for our fellow Jewish family members.