One of the reasons why Jefferson might conclude with this statement is in order to convey the deep commitment that the Founding Fathers felt towards the new nation. In these lines, we learn that all the men signing the Constitution promise their lives, all of their money and their honour to defending their nation and respecting the Constitution. Not only is this important in order to see how much the men valued the Constitution, but it is also meant to inspire others to sacrifice a lot for the protection and maintenance of the country.
I think that Jetforson concluded with this statement because he wants to make sure that nobody breaks their promise to support and live by the declaration. I hope this helps you!
The Logan family and Mr. Morrison are trying to take a stand against the injustice against blacks by whites that is rapidly building up to a crisis—like the Wallace store boycott, or Mr. Morrison's violent defense of Papa.
