“An agnostic is a doubter. The word is generally applied to those who doubt the verity of accepted religious creeds of faiths. Everyone is an agnostic as to the beliefs or creeds they do not accept.”

Page 2.30
The Dark Side of the Universe, 2007

The Scent of Water (1963), Chapter 13.2

Surefish interview (2002)
Context: I'm caught between the words 'atheistic' and 'agnostic'. I've got no evidence whatever for believing in a God. But I know that all the things I do know are very small compared with the things that I don't know. So maybe there is a God out there. All I know is that if there is, he hasn't shown himself on earth.
But going further than that, I would say that those people who claim that they do know that there is a God have found this claim of theirs the most wonderful excuse for behaving extremely badly. So belief in a God does not seem to me to result automatically in behaving very well.

Religious Belief and Public Morality (1984)
Context: Almost all Americans accept some religious values as a part of our public life. We are a religious people, many of us descended from ancestors who came here expressly to live their religious faith free from coercion or repression. But we are also a people of many religions, with no established church, who hold different beliefs on many matters.
Our public morality, then — the moral standards we maintain for everyone, not just the ones we insist on in our private lives — depends on a consensus view of right and wrong. The values derived from religious belief will not — and should not — be accepted as part of the public morality unless they are shared by the pluralistic community at large, by consensus.
That those values happen to be religious values does not deny them acceptability as a part of this consensus. But it does not require their acceptability, either.

The New York Times (3 December 1978)

"The Holy Dimension", p. 335 - 336
Moral Grandeur and Spiritual Audacity: Essays (1997)
Context: There are many creeds but only one faith. Creeds may change, develop, and grow flat, while the substance of faith remains the same in all ages. The overgrowth of creed may bring about the disintegration of that substance. The proper relation is a minimum of creed and a maximum of faith.

But if you don’t know, you don’t know. That’s what an ignoramus is. If you have an open mind close it, would you please, before you destroy yourself. Close it.

"Scripture Is Sufficient" https://www.gty.org/library/sermons-library/80-420/scripture-is-sufficient (1 March 2015), Grace to You
2010s

The Liberty of Man, Woman and Child (1877)
Context: There has never been upon the earth a generation of free men and women. It is not yet time to write a creed. Wait until the chains are broken — until dungeons are not regarded as temples. Wait until solemnity is not mistaken for wisdom — until mental cowardice ceases to be known as reverence. Wait until the living are considered the equals of the dead — until the cradle takes precedence of the coffin. Wait until what we know can be spoken without regard to what others may believe. Wait until teachers take the place of preachers — until followers become investigators. Wait until the world is free before you write a creed.
In this creed there will be but one word — Liberty.

"The Holy Dimension", p. 335 - 336
Moral Grandeur and Spiritual Audacity: Essays (1997)
Context: There are many creeds but only one faith. Creeds may change, develop, and grow flat, while the substance of faith remains the same in all ages. The overgrowth of creed may bring about the disintegration of that substance. The proper relation is a minimum of creed and a maximum of faith.