The purposes of this government are stated right up front.
"We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defense, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America."
These are the purposes of the CONSTITUTION, not the government. The Constitution was established to PROTECT our freedoms from government, foreign and domestic. The government is not you friend - never has been never will be. The Constitution created a government that was carefully limited. Our founders knew all to well that government is like a fox guarding the hen house, so the Constitution put a strong and short chain on the fox.
After 250 years, the chain has been rendered almost useless and the fox is now in the hen house wreaking havoc.