Watch, read, conclude.

An except from the Jonathan Miller PBS series "A History of Disbelief." Take careful note of the quotations of John Adams and Thomas Jefferson:

Both quotations are bogus.

The Adams quotation as presented in the video:

"God is an essence we know nothing of. Until this awful blasphemy is got rid of, there will never be any liberal science in the world."

The Adams quotation as presented in a collection of correspondence between John Adams and Thomas Jefferson:

The Europeans are all deeply tainted with prejudices both Ecclesiastical, and Temporal which they can never get rid of; they are all infected with Episcopal and Presbyterian Creeds and confessions of faith, They all believe that great principle which has produced this boundless universe. Newtons universe, and Hershells universe, came down to this little Ball, to be spit-upon by Jews; and untill this awful blasphemy is got rid of, there can never be any liberal science in the world.
(letter to Thomas Jefferson, January 22, 1825) (italics added for emphasis)

I suppose I should note that the first part of the quotation in the video is from an entirely different document. Here is that document (in full, as far as I can tell), from a collection of Adams' works.

When we say God is a spirit, we know what we mean, as well as we do when we say that the pyramids of Egypt are matter. Let us be content, therefore, to believe him to be a spirit, that is, an essence we know nothing of, in which originally and necessarily reside all energy, all power, all capacity, all activity, all wisdom, all goodness.
(John Adams, January 17, 1820)(italics added for emphasis)

The video account produces a quotation very friendly to atheism and unfriendly even to Deism, and they unblushingly cobble together quotations that were five years apart.

Obviously, the "blasphemy" Adams talked about was not the god of unknown essence, but the deity of Jesus of Nazareth. The way the film presents the quotation, one would never know.

****

The Jefferson quotation as presented in the video:

"The clergy believe that any power confided in me will be exerted in opposition to their schemes. And they believe rightly."

Jefferson's letter to Benjamin Rush:

I promised you a letter on Christianity, which I have not forgotten. On the contrary, it is because I have reflected on it, that I find much more time necessary for it than I can at present dispose of. I have a view of the subject which ought to displease neither the rational Christian nor Deists, and would reconcile many to a character they have too hastily rejected. I do not know that it would reconcile the genus irritabile vatum who are all in arms against me. Their hostility is on too interesting ground to be softened. The delusion into which the X.Y.Z. plot shewed it possible to push the people; the successful experiment made under the prevalence of that delusion on the clause of the constitution, which, while it secured the freedom of the press, covered also the freedom of religion, had given to the clergy a very favorite hope of obtaining an establishment of a particular form of Christianity thro' the U.S.; and as every sect believes its own form the true one, every one perhaps hoped for his own, but especially the Episcopalians & Congregationalists. The returning good sense of our country threatens abortion to their hopes, & they believe that any portion of power confided to me, will be exerted in opposition to their schemes. And they believe rightly; for I have sworn upon the altar of god, eternal hostility against every form of tyranny over the mind of man. But this is all they have to fear from me: & enough too in their opinion, & this is the cause of their printing lying pamphlets against me, forging conversations for me with Mazzei, Bishop Madison, &c., which are absolute falsehoods without a circumstance of truth to rest on; falsehoods, too, of which I acquit Mazzei & Bishop Madison, for they are men of truth.
(positiveatheism.org)

The video paints Jefferson in opposition to all the purposes of the clergy, omitting the context pointing directly at the establishment of a national religion and Jefferson's reference to swearing "upon the altar of god." I suppose it wouldn't do to let Jefferson swear on the altar of god since the idea is to make him appear hostile to religion generally.

The Miller production takes substantial liberties with these quotations, either because of poor research, ineptitude or overt dishonesty. Words are added without any admission of tampering with the text, context is dropped, and quotations from separate documents are combined to give new and foreign meaning to both.