John Locke, answered from the texts and cited to the page.
The argument runs through the Two Treatises and the Essay in identical form. Men are God's creatures, sent into the world about His business; we are His workmanship, and the law of nature is His declaration to His rational creatures of what is required for the preservation of mankind. From equal createdness — that "Creatures of the same species and rank, promiscuously born to all the same advantages of Nature, and the use of the same faculties, should also be equal one amongst another without Subordination or Subjection" (T II.II.4) — equality and natural freedom follow.
Without the workmanship doctrine the equality premise has no ground; with it, the entire structure (life, liberty, property; the executive right to punish; the institution of government by compact; the right of resistance) follows.12
Eccl. Pol. Lib. 1. 6. But though this be a State of Liberty, yet it is not a State of Licence, though Man in that State have an uncontroleable Liberty, to dispose of his Person or Possessions, yet he has not Liberty to destroy himself, or so much as any Creature in his Possession, but where some nobler use, than its bare Preservation calls for it.Two Treatises of Government, pp. 219–220
It is an existentialist proposition, which men have not thought it worth while to question seriously until our own day, and it relies not so much on the proved existence of a Deity as upon the possibility of taking what might be called a synoptic view of the world, more vulgarly a God's-eye view of what happens among men here on earth.Two Treatises of Government, pp. 81–82
The most contested ground in Locke scholarship. Strauss reads the natural-law surface as cover for a secret-Hobbesian individualist core and argues that I covertly grounded rights in self-preservation rather than in divine declaration. Macpherson reads the surface as ideology of unlimited capitalist appropriation. Dunn, Tully, Ashcraft, and Waldron defend the theological reading as the actual ground of the texts. The debate is whether the political conclusions can be re-grounded on secular foundations (Kant, Rawls) or whether the equality argument fails without the workmanship premise it actually deploys.