The Founders went to great lengths to make sure our rights to privacy and liberty were protected. They had just experienced the effects of a repressive regime: being forced to house enemy soldiers in their homes; soldiers searching through their papers and personal items without any just cause; sailors being kidnapped and forced to serve in the King's Navy; and the list goes on. Of all the powers listed in the Constitution, only the powers granted to maintain a military and protect our shores concern the government protecting us.
All the other powers are listed to protect we the people from the overbearing and overreaching arms of a power-hungry government. Many people claim that they don't care if the government listens to their phone calls, reads their emails, collects their DNA, or spies on them in a variety of other ways. They always claim: "well I've done nothing wrong, I have nothing to hide." Try telling that to the Jews in Germany during WWII, what had they done wrong? What did they have to hide? Or tell that to the millions of people that Stalin had sent to his gulags and eliminated. Try telling that to the families I met in Romania who had their fathers kidnapped out of their apartments in the pitch-black of the night simply because he looked at the wrong person in the wrong way. Tell that to the Americans who were hung as spies and traitors during the War for Independence.
Simply put, our God-given rights are to protect us from the greed of men who have tasted power and want as much of it as they can get, no matter the price to be paid by other people. We are to have a government "of the people, by the people, and for the people" to protect we the people from the evils of government itself.
Amendment 4 of the Bill of Rights: The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.