S. R. Faruqi:

[See {546,1}; {611,5}.]

FWP:

SETS == EXCLAMATION; HUMOR
MOTIFS == RELIGIONS
NAMES
TERMS

[This verse does not appear in SSA.]

I'm truly sorry that SRF didn't make room for this one. Its great appeal is in the speaker's impatient tone: 'Have you been living under a rock? Don't you keep up on things at all? Why are you asking about such completely stale news, when all the gossip-mongers have long ago beaten it to death and moved on?' Any possible shock value of Mir's renouncing Islam is so completely negated by this condescendingly impatient treatment that the effect is wonderfully funny. 'Mir's behavior is such old news!' In my view this verse is, if recited in an appropriately jaded or disdainful tone, quite funny.

The crucial word in the first line is that little ab ; only in retrospect (after we've encountered the kab kā ) do we realize that it's actually the pivot on which the whole verse turns.

And while we're enjoying verses about infidels, here's another, also not chosen by SRF, that I very much relish; it's {846,8}, from the second divan:

but chīz kyā kih jis ko ḳhudā mānte haiñ sab
ḳhvush-ětiqād kitne haiñ hindūsitāñ ke log

[what is an idol, that they all consider it to be the Lord!?
how well-believing are the people of Hindustan?!]

When we consider the multivalent possibilities of kyā in the first line and kitne in the second line, it's easy to see that this verse can be read as an expression of wondering admiration for idol-worship (even though it may imply credulousness!), a sarcastic rejection of idol-worship, or a question about the nature and validity of idol-worship. Needless to say, in the context of the ghazal world the first possibility is especially compelling; but the hovering presence of the others adds several layers of piquancy to the verse.

And as for the detailed description of Mir's becoming an infidel, here's another explicit endorsement of just such behavior, from the fifth divan [{1679,8}]:

dar pah ḥaram ke kushūd nahīñ to dair meñ jā kar kāfir ho
qashqah kheñcho pothī paṛho zunnār gale se bañdhāʾo tum

[if at the door of the Ka'bah there's no opening, then go into a temple and become an infidel,
put on a forehead-mark, read a holy-book, have a sacred-thread tied around your neck]

And let's not forget

{1851,1}.

Note for grammar fans: I've translated the colloquial kab kā as 'it's been ages since', but actually of course it's short for something like kab kā vāqiʿah hai kih , 'it's an event from when?'-- it's something so far in the past that its date doesn't even come to mind.