Please read Alexey Sklyarenko's annotations on Pale Fire, Ada and other Nabokov works here.
In Canto One of his poem John Shade (the poet in VN's novel Pale Fire, 1962) speaks of his childhood and says that his God died young:
My God died young. Theolatry I found
Degrading, and its premises, unsound.
No free man needs a God; but was I free?
How fully I felt nature glued to me
And how my childish palate loved the taste
Half-fish, half-honey, of that golden paste!
My picture book was at an early age
The painted parchment papering our cage:
Mauve rings around the moon; blood-orange sun