I'm not a psychiatrist, but perhaps I can offer some insight. I'll keep "depression" from your later post because it adds a bit of depth.
If a patient walked in with a chief complaint of "depression" and opened with a line about an invisible man, the doctor would most likely be interested in this. After all, religious people generally do not describe their deities as invisible men, and the patient is bringing this up as the first topic for discussion. Medical professionals are trained to give follow-up questions to explore patients' symptoms more deeply, so this symptom would definitely warrant further questioning.
The first thought on my mind after "Well, there's an invisible man I talk to" would be to determine whether this is more a delusion or hallucination, or both. Is the patient actually hearing a voice? Are they seeing anything (invisible to everyone else
)? If yes, is the voice telling them to do anything? However, from the dialogue given, delusion would be the more likely consideration.
At this point the differential is still rather wide. If hallucination is suspected, then the psychotic disorders are on the table. This includes schizophrenia, schizoaffective (basically a combo of schizophrenia and depression), major depression with psychotic features, drug use (can cause both depression and hallucinations), multiple medical disorders, etc. If delusion is suspected, then we'd be looking at stuff like bipolar, schizophrenia/schizoaffective, major depression with psychotic features, delusional disorder, etc.
Sticking with delusion, the important question here would be the timing of it. Is the delusion always present? Does it only appear when the patient is depressed? Does it only appear when the patient is feeling energetic (and not sleeping, and buying expensive things)? Does the delusion comes before the mood changes, or do the mood changes come before the delusion?
Also important is how the patient is behaving. Are they very anxious with pressured speech? Do they jump from topic to topic without forming coherent thoughts? Are they flat and expressionless? Are they talking like an otherwise rational human being?
So these would be some of the considerations going into the first break point.
The second part of the dialogue certainly changes the approach. And no, the church comment is not a good reason to stop investigating. The next most logical response would be to establish concretely whether "talking to an invisible man" is equivalent to "praying to God," (rather than just assuming it) and go from there.
Assuming that is
what the patient meant, that doesn't mean the patient is delusion free. Religious delusions are common enough that it's worth determining whether the patient is describing a religious delusion
or a religious belief
. If it's the former, all our original considerations are back on the table. If it's the latter, we're still not done.
If the patient is simply talking about religious belief, it's worth investigating why the patient brought that belief up immediately and in such an unconventional way, without clarifying that belief when it became clear the doctor didn't understand that they were describing God. Is their religious belief causing some sort of life issue that's central to the depression? Was the patient intentionally going on a tangent to avoid discussing their real underlying issues?
After all, the patient is at the appointment for a reason, and that reason doesn't disappear simply because the person is religious. If the belief isn't the reason they're there, then what brought them to the psychiatrist? If it's the depression, and the patient intentionally wasted 15 minutes of the appointment to avoid talking about why they're depressed, then that gives the doctor some important information about the patient.
So yeah, it's definitely significant, delusion or not. As for drugs, it would depend on what the final diagnosis is. If it's not a delusion, then we're looking at treating the depression (or whatever it turns out to be.) If it's a true delusion, then antipsychotics might be warranted, depending on the particulars of the case and the final diagnosis.