“Coincidence is God's way of remaining anonymous.”
Director's commentary for Dragonfly.
The source generally (but falsely) cited is Einstein's The World As I See It http://en.wikipedia.org/wiki/The_World_as_I_See_It_(book) (1949). The quotation is probably a translation of "Der Zufall ist das Pseudonym, das der liebe Gott wählt, wenn er inkognito bleiben will" (attributed to Albert Schweitzer).
Disputed
“Coincidence is God's way of remaining anonymous.”
Director's commentary for Dragonfly.
“Who was it that said that coincidence was just God’s way of remaining anonymous?”
Source: The Goldfinch
“Coincidences are God's way of getting our attention.”
“Whoever created Bitcoin wanted to remain anonymous”
Source: https://www.nasdaq.com/articles/who-is-satoshi-nakamoto
“There are only two ways of telling the complete truth--anonymously and posthumously.”
Source: The Foundation series (1951–1993), Foundation’s Edge (1982), Chapter 14 “Forward!” section 1, p. 281