|A Reddit image, depicting “closet atheism” as compared to “closet homosexuality”, the latter of which is publicly an “open” and an accepted status presently, from a 2015 thread post (Ѻ) “Who is in the closet?”.|
The following are related quotes:
“How comes it, then, that Laplace was an atheist? At the Institute neither he nor Monge, nor Berthollet, nor Lagrange believed in god. But they do not like to say so.”— Napoleon Bonaparte (c.1814), dialogue with Gaspard Gourgaud
“If we need an atheist for a debate, I go to the philosophy department. The physics department isn’t much use.”— Robert Griffiths (1987) 
“At the University of California, Berkeley, where I was a professor for 18 years, we had 50 chemistry professors. But for many years there was only who was willing to publicly identify himself as an atheist, my good friend Robert Harris. A more recent addition to the Berkeley chemistry faculty is a second open atheist, Richard Saykally.”— Henry Schaefer (2003), Science and Christianity: Conflict or Coherence? 
“We are living in a totally ridiculous world. We have all kinds of things from horoscopes to Zen Buddhism to faith healers to religions to what have you. The whole world around us is full of nonsense, baloney, big speak and what have you. The fact that I'm busy in science has little or nothing to do with religion. In fact, I protect myself, I don't want to have to do with religion. Because once I start with that, I don't know where it will end. But probably I will be burned or shot or something in the end. I don't want anything to do with it. I talk about things I can observe and other things I can predict and for the rest you can have it.”— Martinus Veltman (2004) interview (Ѻ) with Harold Kroto (quote, 10:05-) (Ѻ)
“Closet atheism, take it from me, is one of the most comfortable positions for one's psyche in America. No quarrels, no arguments, especially with the immediate family, and one gets along fine with bosses, other acquaintances and the larger society. After all, buttonholed at a cocktail party, it's much more chic to proclaim one is an "agnostic" than an atheist! The term agnostic carries within it a kind of detached, above-it-all wisdom, rather than the total capitulation to feigned ignorance truly at its core. In my closet years, up until I went public in the article “My Path to Atheism” (1992), life was fine. I got on famously with my parents, and experienced no problems at work or in the larger community. The publication of the article changed all that, especially with my family.”— Philip Stahl (2007), Atheism: a Beginner’s Handbook (§3: The Downsides of Closet Atheism) 
1. (a) Griffiths, Robert. (1987). “Article”, Christianity Today, Apr 3.
(b) Schaefer, Henry F. (2003). Science and Christianity: Conflict or Coherence? (debate, pg. 26; Harris, pg. 77). The Apollos Trust.
2. (a) Schaefer, Henry F. (2003). Science and Christianity: Conflict or Coherence? (debate, pg. 26; Harris, pg. 77). The Apollos Trust.
(b) Roberg A. Harris (faculty) – UC Berkeley.
(c) Richard Saykally (faculty) – UC Berkeley.
2. (a) Stahl, Philip A. (1992). “My Path to Atheism”, The American Atheism Magazine, Jun.
(b) Stahl, Philip A. (2007). Atheism: a Beginner’s Handbook – All You Wanted to Know About Atheism and Why (§3: The Downsides of Closet Atheism, pgs. 112-). iUniverse.
● Closet atheism – Conservapedia.