Natural rights can be defined through the writing of John Locke:
"Any single man must judge for himself whether circumstances warrant obedience or resistance to the commands of the civil magistrate; we are all qualified, entitled, and morally obliged to evaluate the conduct of our rulers. This political judgment, moreover, is not simply or primarily a right, but like self-preservation, a duty to God. As such it is a judgment that men cannot part with according to the God of Nature. It is the first and foremost of our inalienable rights without which we can preserve no other."
(John Locke)
"... whenever the Legislators endeavour to take away, and destroy the Property of the People, or to reduce them to Slavery under Arbitrary Power, they put themselves into a state of War with the People, who are thereupon absolved from any farther Obedience ... [Power then] devolves to the People, who have a Right to resume their original Liberty, and, by the Establishment of a new Legislative (such as they shall think fit) provide for their own Safety and Security, which is the end for which they are in Society."
(John Locke)
"He that in the state of nature, would take away that freedom, that belongs to anyone in that state, must necessarily be supposed to have a design to take away everything else, that freedom being the foundation of all the rest. As he that in the state of society, would take away the freedom belonging to those of that society or commonwealth, must be supposed to design to take away from them everything else".
(John Locke, Second Treatise, Chapter 3)
Or, um... that is to say that anyone who would seek to take away a freedom or a "Right", granted by God to His creation, would seek to take away everything else that a person possesses under such a ruling body. Or, to put it another way, when a governing body begins restricting the rights of the governed, it must be concluded that the governing body does not have the best interests of the governed in mind. Furthermore, John Locke was very much vested in the idea that men have the capacity to make absolutely stupid decisions, and such was their right and liberty to do:
"The Care therefore of every man's Soul belongs unto himself, and is to be left unto himself. But what if he neglect the Care of his Soul? I answer, What if he neglects the Care of his Health, or of his Estate, which things are nearlier related to the Government of the Magistrate than the other? Will the magistrate provide by an express Law, That such an one shall not become poor or sick? Laws provide, as much as is possible, that the Goods and Health of Subjects be not injured by the Fraud and Violence of others; they do not guard them from the Negligence or Ill-husbandry of the Possessors themselves."
(John Locke)
....which cannot be taken as a theological statement without making one's head hurt, but it does apply to social governance under a Republic.
Are we so free that we can make stupid decisions that do not directly harm anyone else without the government attempting to legislate in order to stop such decisions from being made in the first place? I have to buckle my seatbelt or I'll get a ticket. What happened to natural rights?
To sum up, Thomas Paine, in his work, aptly titled "Common Sense", said:
Society in every state is a blessing, but Government, even in its best state, is but a necessary evil; in its worst state an intolerable one: for when we suffer, or are exposed to the same miseries by a government, which we might expect in a country without a government, our calamity is heightened by reflecting that we furnish the means by which we suffer. Government, like dress, is the badge of lost innocence; the palaces of kings are built upon the ruins of the bowers of paradise. For were the impulses of conscience clear, uniform and irresistibly obeyed, man would need no other lawgiver; but that not being the case, he finds it necessary to surrender up a part of his property to furnish means for the protection of the rest; and this he is induced to do by the same prudence which in every other case advises him, out of two evils to choose the least. Wherefore, security being the true design and end of government, it unanswerably follows that whatever form thereof appears most likely to ensure it to us, with the least expense and greatest benefit, is preferable to all others.
In order to gain a clear and just idea of the design and end of government, let us suppose a small number of persons settled in some sequestered part of the earth, unconnected with the rest; they will then represent the first peopling of any country, or of the world. In this state of natural liberty, society will be their first thought. A thousand motives will excite them thereto; the strength of one man is so unequal to his wants, and his mind so unfitted for perpetual solitude, that he is soon obliged to seek assistance and relief of another, who in his turn requires the same. Four or five united would be able to raise a tolerable dwelling in the midst of a wilderness, but one man might labour out the common period of life without accomplishing any thing; when he had felled his timber he could not remove it, nor erect it after it was removed; hunger in the mean time would urge him to quit his work, and every different want would call him a different way. Disease, nay even misfortune, would be death; for, though neither might be mortal, yet either would disable him from living, and reduce him to a state in which he might rather be said to perish than to die.
Thus necessity, like a gravitating power, would soon form our newly arrived emigrants into society, the reciprocal blessings of which would supersede, and render the obligations of law and government unnecessary while they remained perfectly just to each other; but as nothing but Heaven is impregnable to vice, it will unavoidably happen that in proportion as they surmount the first difficulties of emigration, which bound them together in a common cause, they will begin to relax in their duty and attachment to each other: and this remissness will point out the necessity of establishing some form of government to supply the defect of moral virtue.
I'll leave the rest to the reader, as it is quite an interesting treatise which can be found
Here.