
Faust and Gretchen in the garden (1808) during which time she asks the so-called "Gretchen question", namely: what is your opinion on religion and do you believe in God? (Painting James Tissot, 1861) (Ѻ) The riddled poetic answer to which Faust gives, supposedly, being indicative of his own views, to some extent.

Faust and Gretchen in the garden (1808) during which time she asks the so-called "Gretchen question", namely: what is your opinion on religion and do you believe in God? (Painting James Tissot, 1861) (Ѻ) The riddled poetic answer to which Faust gives, supposedly, being indicative of his own views, to some extent.

In questions, Gretchen question, or Gretchenfrage (German), meaning “crutch question”, refers to the religion and or god belief question a person asks their new prospective lover; the question is presented in Goethe's Faust, Part One (1808).

Overview
In 1808, Goethe, in Faust, Part One, gives the new lovers encounter, in the story, when the figure Margarete, called Gretchen, asks the main character Heinrich Faust about his attitude to religion and if he believe in god; specifically: [1]

“Now tell me how you feel about religion? You are cordially good man, But I think you do not think much of it?”

Gretchen, is a very young girl who is being courted by the older, respectable scientist. After they have already met several times and even kissed, but not yet slept together, Gretchen makes her question to Faust. [2] She asks him directly how he stood with God and religion, to which he answers: [3]

“Leave that, child! Truly, my love is tender;
For love, blood and life would I surrender,
For Faith and Church, I grant to each his own.

My darling, who shall dare
‘I believe in God!’ to say?
Ask priest or sage the answer to declare,
And it will seem a mocking play,
A sarcasm on the asker.

Hear me not falsely, sweetest countenance!
Who dare express Him?
And who profess Him,
Saying, I believe in Him?
Who, feeling, seeing,
Deny His being,
Saying: I believe Him not!

As to whether Goethe, himself, believed in the existence of god, several citations seem to point to Goethe’s Faust and this so-called Gretchen question, as his views on the matter.

This answer, according to Adolf Just, is an “evasive, entirely obscure answer”, of Faust, which does “not satisfy the reader either.” [3]

In 1937, Max Planck, aged 79, in his “Religion and Natural Science” lecture, opens to the Gretchen question, as a sort of ice breaker, as follows: [4]

“ ‘Tell me: how do you stand on religion?’ — If Goethe’s Faust contains at all a simple phrase that captivates even a sophisticated listener and arouses a hidden tension within him, it must be this worried question of an innocent girl, in fear for her newly-found happiness, to her lover whom she recognizes as a higher authority.”

Planck, here, at this point, to note is anti-atheistic, in his lecture, and openly says he doesn't want to ruffle and feathers, so to say; therein attempting to console the religious person in the context of growing science; here, however, we see Planck expressing his own "hidden tension" on the issue, even as an aged man.

Quotes
The following are related quotes:

“To ask the ‘Gretchen question’ is to ask about someone’s deepest religious or political convictions; from Goethe, Faust, I.—MEB]”
— Eugene Boring (2009), note (pg. 150) (Ѻ) in translation of Udo Schnelle’s Theology of the New Testament

References
1. (a) Faust (verse: 3417) (German → English) – SoftScience.at.
(b) Barbour, Julian. (2000). The End of Time: the Next Revolution in Physics (pg. 338). Oxford University Press.
2. Gretchenferage (German → English) – Wikipedia.
3. Just, Adolf. (1996). Return to Paradise: Paradise Regained (pg. 268). Health Research Books.
4. Planck, Max. (1937). “Religion and Natural Science”, lecture, May; in: Scientific Autobiography and Other Papers (translator: Frank Gaynor) (§6:151-50; pg. 125). Philosophical Library, 1949.