I understand your perspective in asking this question: some pieces of literature have non-character elements that are so strong some scholars analyze these as inferred characters. An example of this that comes readily to mind is the house in Hawthorne's The House of the Seven Gables; the significance of the house as an inferred character is confirmed in the title as well as in the opening lines and paragraphs of the story:
HALFWAY down a by-street of one of our New England towns stands a rusty wooden house, with seven acutely peaked gables, facing towards various points of the compass, and a huge, clustered chimney in the midst.
The question at hand is: Is there any evidence in the text of The Crucible to confirm God as an unstated, inferred character? One way to determine this is to examine--as above--the opening lines of the play. Upon doing so, we discover that Miller presents no textual indications that he intends God to be given the status of a character: God isn't even mentioned or even indirectly inferred in the opening portion of the play. On the contrary, the spiritual entity that is inferred is God's theological counterpart. Thus God can not properly be considered an inferred character as there is no textual element that suggests or establishes this in the exposition, which is where such an inference would be established as we've seen in The House of Seven Gables; thus, you must be content with God as a theme or motif. These conclusions are represented well by some excerpts from Parris's early conversation with Abigail:
PARRIS: Child. Sit you down. Now look you, child-if you trafficked with spirits in the forest, I must know it, for surely my enemies will, and they’ll ruin me with it… Abigail, do you understand that I have many enemies? ... in the midst of such disruption, my own household is discovered to be the very center of some obscene practice. Abominations are done in the forest ... I saw Tituba waving her arms over the fire when I came on you; ... And I heard a screeching and gibberish comin’ from her mouth ... whatever abomination you have done, give me all of it now, ....