"Doth God exact day-labour, light denied..."
See in text (Text of the Poem)
In this line, Milton's speaker asks the question, not God. The long and complex sentence beginning with "When I consider how my light is spent" leads the poet to fondly, or foolishly, ask: "Doth God exact day-labour, light denied?" After this question, the first sentence of the sonnet ends with a full stop. All the rest of the sonnet is supposedly spoken by an invisible spirit or angel he calls "Patience." Milton's conclusion suggests that he has made appropriate use of his "one talent" and that God will not scold or "chide" him for wasting it.