That to secure these rights, governments are instituted among men, deriving their just powers from the consent of the governed; that whenever any form of government becomes destructive of these ends, it is the right of the people to alter or to abolish it, and to institute new government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their safety and happiness. what is the main idea of this passage from the declaration of independence?

Let's first implement sectional analysis of the text, then we can examine the general meaning of the excerpt. The excerpt begins with the basic rights of governments must form before their people. Then, it follows the performance  and the end result of this action. According to this basic idea of fair governance, people have the rights to replace their government if the government is a tyranny. And the substitute have to be a new government which brings safety and happiness to its people.

The general meaning is the justification of a revolt against United Kingdom during that time and the document as this introductory part confirms laid the foundation of this idea to address all the people living in the new ground.          

People have the right to determine the best form of government for them

Explanation:

c. a group of tribes that formed a confederacy

pulling in the reader is important