Subtle is the Lord, but malicious He is not.

Remark made during Einstein's first visit to Princeton University (April 1921) as quoted in Einstein (1973) by R. W. Clark, Ch. 14. "God is slick, but he ain't mean" is a variant translation of this (1946) Unsourced variant: "God is subtle but he is not malicious."

When asked what he meant by this he replied. "Nature hides her secret because of her essential loftiness, but not by means of ruse." (Die Natur verbirgt ihr Geheimnis durch die Erhabenheit ihres Wesens, aber nicht durch List.) As quoted in Subtle is the Lord — The Science and the Life of Albert Einstein (1982) by Abraham Pais einsteinandreligion.com | Originally said to Princeton University mathematics professor Oscar Veblen, May 1921, while Einstein was in Princeton for a series of lectures, upon hearing that an experimental result by Dayton C. Miller of Cleveland, if true, would contradict his theory of gravitation. But the claimed discrepancy was quite small and required special circumstances (hence Einsteins's remark). The result turned out to be false. Some say by this remark Einstein meant that Nature hides her secrets by being subtle, while others say he meant that nature is mischievous but not bent on trickery. [The Yale Book of Quotations, ed. Fred R. Shapiro, 2006] | As quoted in Cherished Illusions (2005) by Sarah Stern, p. 109 | I have second thoughts. Maybe God is malicious. | Said to Valentine Bargmann, as quoted in Einstein in America (1985) by Jamie Sayen, p. 51, indicating that God leads people to believe they understand things that they actually are far from understanding; also in The Yale Book of Quotations (2006), ed. Fred R. Shapiro

God may be sophisticated, but he's not malicious.