How is the Declaration of Independence a neoclassical/Age of Reason document?

The Age of Reason came about in response to the traditional values of strict control with religion and government. The Declaration of Independence was a byproduct of this movement and was a quintessential Age of Reason document. To begin, strict religious and governmental control defined life in colonial America leading up to the revolution. The Church of England played a crucial role in the government of the colonies through the crown and the overall way of life of the individual. The Age of Reason produced the idea that each individual has their own reason and is granted rights at birth.
The Declaration of Independence specifically cites ideas of the Age of Reason. One instance is "Laws of Nature and of Nature's God entitle them." This states clearly the idea that the individual is granted certain freedoms and that these freedoms are inherent; one does not need to practice a certain religion or follow governmental regulations to be granted these rights. Moreover, they are "endowed by their creator." This goes against the prior view of salvation gained through practice. The Puritanical view of strict religious structure was now obsolete. For these reasons, the Declaration of Independence was a product of the Age of Reason.
https://www.livescience.com/4995-declaration-independence-changed-world.html

The Declaration of Independence was written in the neoclassical/Age of Reason period in history.  This period of time was defined by the movement toward the belief that people were rational beings who could arrive at a conclusion through the process of logical thought.
In essence, the document rejected the belief that it was a sin to question theocracy and one’s own subjugation by God and other divine rulers. Instead, there was a strong move toward the values outlined in the Declaration of Independence: freedom of speech, freedom to question laws and institutions, and the freedom to do things for the good of all people.  In fact, this move toward equality in American society was quite revolutionary in that it rejected a hierarchy, rigid social structures were imposed by slaveowners in the colonies and by British rulers back in England.
In keeping with the rationalist literature that was beginning to emerge, the language of the Declaration of Independence attempted to support rationalist ideals. For example, the author of the Declaration, Thomas Jefferson, based his writing not on some erroneous belief of an afterlife, but rather on the science and philosophy of the day, which centered around equality in government, the ethical treatment of people, and making social and political improvements. The structure of the document was clear and logical; it identified the purpose of the document, it outlined the theory of what constitutes a good government, and it declared their individual rights as citizens of that government. Next, it listed the reasons for their grievances against Great Britain, which were many.  Finally, it established their sovereignty as a world nation.
When drafting the Declaration of Independence, Thomas Jefferson drew upon the ideas of other influential thinkers of the time, including John Locke, a known writer and distributor of rationalist literature. He made sure to consider the influential ideas brought about by Enlightenment.  Essentially, he turned the political theories and philosophy of 18th-century Europe into reality.