How does the Declaration of Independence reflect Jefferson's faith in reason?

It influences it alot.

Explanation:

Reason is because he write it.

He mentions the laws of nature (1), he states that all men are created equal and that they're endowed with unalienable rights (2), and that governments derive their power from the consent of the governed (3). These are principles that could be derived by reason alone. They're foreign to the ways of tradition which believed in the divine right of kings, aristocracy, and a Christian God, not a god of nature.