In 1776, Thomas Jefferson wrote the Declaration of Independence which included the phrase "all men are created equal". Since the phrase eludes to creation, I always assumed that the phrase must have a Christian origin, perhaps a restatement of a verse from the Bible, or a paraphrase from some medieval monk. But at the same time, Jefferson himself diverged from traditional Christianity and was influenced by Voltaire who was a strong critic of religion during the age of enlightenment.
So what is the true origin of this phrase, does it derive from Christianity, or from secular humanism?
The oldest version I know of is from John Ball's sermon to the rebels in the Peasant Revolt of 1381, led by Wat Tyler. In modern English,
When Adam delved and Eve span, who was then the gentleman [i.e., nobleman]? From the beginning all men were created equal by nature, and that servitude had been introduced by the unjust and evil oppression of men, against the will of God, who, if it had pleased Him to create serfs, surely in the beginning of the world would have appointed who should be a serf and who a lord.
Whether or not Ball had used the same language earlier, he had certainly preached similar ideas:
My good friends, matters cannot go well in England until all things shall be in common; when there shall be neither vassals nor lords; when the lords shall be no more masters than ourselves. How ill they behave to us! for what reason do they hold us thus in bondage? Are we not all descended from the same parents, Adam and Eve? And what can they show, or what reason can they give, why they should be more masters than ourselves?
being a typical Ball sermon. After the revolt was suppressed, Ball was arrested and tried for treason. Found guilty, he was, still unrepentant, hung, drawn, and quartered.
Similar sentiments, echoing the same language were often repeated by English radicals before and during the English Civil War. This is covered in plentiful detail in Christopher Hill, The World Turned Upside Down: Radical Ideas During the English Revolution, Temple Smith, 1972 (reprinted Penguin, 2020).
Depsite it's earlier origin, Jefferson's use of the term is certainly taken from John Locke and his Two Treatises on Government in which he explains the natural rights of man. In June 1776 Jefferson was working on a rough draft;
When in the course of human events it becomes necessary for a people to advance from that subordination in which they have hitherto remained, & to assume among the powers of the earth the equal & independant station to which the laws of nature & of nature's god entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the change.
We hold these truths to be sacred & undeniable; that all men are created equal & independant, that from that equal creation they derive rights inherent & inalienable, among which are the preservation of life, & liberty, & the pursuit of happiness; that to secure these ends, governments are instituted among men, deriving their just powers from the consent of the governed; that whenever any form of government shall become destructive of these ends, it is the right of the people to alter or to abolish it, & to institute new government, laying it's foundation on such principles & organising it's powers in such form, as to them shall seem most likely to effect their safety & happiness.
But earlier in June the Pennsylvania Gazette had published the work of George Mason on the Virginia Declaration of Rights at the 5th Virginia Convention in Williamsburg, which Jefferson was displeased he could not attend. Mason's words would be published just before Jefferson's draft above was penned;
Section 1. That all men are by nature equally free and independent and have certain inherent rights, of which, when they enter into a state of society, they cannot, by any compact, deprive or divest their posterity; namely, the enjoyment of life and liberty, with the means of acquiring and possessing property, and pursuing and obtaining happiness and safety.
Which is strikingly similar to Jefferson's words (or rather the other way around). Mason, in turn, had also taken the concept from Locke who spoke of our perpetual "state of nature" and its endowed rights to "life, liberty, and property" conveyed to us as humans.
Some examples from Locke's Treatises;
there can be but one supreme power, which is the legislative, to which all the rest are and must be subordinate, yet the legislative being only a fiduciary power to act for certain ends, there remains still in the people a supreme power to remove or alter the legislative, when they find the legislative act contrary to the trust reposed in them: for all power given with trust for the attaining an end, being limited by that end, whenever that end is manifestly neglected, or opposed, the trust must necessarily be forfeited, and the power devolve into the hands of those that gave it, who may place it anew where they shall think best for their safety and security. (This is very similar to Jefferson's Declaration draft)
The state of nature has a law of nature to govern it, which obliges every one: and reason, which is that law, teaches all mankind, who will but consult it, that being all equal and independent, no one ought to harm another in his life, health, liberty, or possessions: for men being all the workmanship of one omnipotent, and infinitely wise maker... (Here we see another connection to the draft of being "equal and independent" and having a right from nature to "life, health, liberty, or possessions")
Every one, as he is bound to preserve himself, and not to quit his station wilfully, so by the like reason, when his own preservation comes not in competition, ought he, as much as he can, to preserve the rest of mankind, and may not, unless it be to do justice on an offender, take away, or impair the life, or what tends to the preservation of the life, the liberty, health, limb, or goods of another.