Was Ghalib an atheist?

Former Chief Justice Katju has suggested that Ghalib was opposed to feudalism and progressive in his views. Does the following verse support the notion that, like Marx, he considered Religion a mere opiate for the Masses?

{174,10}*

ham ko maʿlūm hai jannat kī ḥaqīqat lekin
dil ke ḳhvush rakhne ko ġhālib yih ḳhayāl achchhā hai

1) we know the reality/truth of Paradise, but

2) to keep the heart happy, Ghalib, this idea is good

Islamic scholars make a distinction between metaphorical (majazi) understanding- where there is a contextual indicator of some shared fact of experience- and literal (haqiqi) truth. Since human beings have no shared or objective experience of the Unseen realm- which includes Paradise- Scriptural declarations on such topics can only be taken literally not metaphorically.

Thus the meaning here is- 'We know that Paradise exists and has certain properties as a matter of literal truth, rather than figuring in Scripture as a metaphor or symbol for something else, but, nevertheless, to keep the heart happy this dream or imagining (khayal) is good.' 

What precisely is the dream or imagining which keeps the heart happy? It is the dream or imagining of Heaven- as opposed to the Revelation of its literal truth. Why is it the heart- as opposed to the brain or liver- which is being made happy? Well, the heart has a special importance as being the place where something higher, purer and more Spiritual intermingles with something lower, material, and impure- e.g. 'Ruh' and 'nafs'.

A meta-metaphor- i.e. a figurative way of speaking about figurative language- operates by making some sort of higher/lower or pure/impure or imaginary/real or noumenon/phenomenon type distinction between its own field of reference and that which is literally true.  

Ghalib is showing that the khayal of Jannat- i.e. human beings', necessarily empirically unsupported, conception of Paradise, as opposed to literal Revelation regarding it- is a meta-metaphor- it is majazi majaz- i.e. it isn't a new ontological category but a sublation away from an erroneous or mischievous one. Furthermore, the happiness of the heart, that it gives rise to, is contextually pinned down to the self abnegation of the lover, his amor fati and will-to-annihilation. In other words, Ghalib's meta-metaphoricity here  affirms orthodoxy and reconciles to it the apparently transgressive element in taghazzul such that a special excellence in Revelation- viz. its suitability to human beings- is brought out because, Ghalib says, the literal nature of Revelation has

1) the property of being understood

2) the further property that any imaginal departure from perfect coincidence with that literal understanding- i.e. any semiotic slippage arising from figurative speech or imaginal conception or the admixture of personal hopes and dreams- has the power to self-correct by producing the longing for its own annihilation such that it only truly tastes happiness in the sure prospect of that annihilation- i.e. though entry into Paradise is not certain, death is and that is good enough. In other words, the Scriptural Revelation of a Paradise which literally exists (but which, as sinners, we may not be certain of entry to) instead of troubling the Ghazal-lover's hearts with anxiety has the opposite effect such that even those who feel themselves certain to be excluded from it gain happiness for their heart merely from the metaphoricity, as opposed to the literal truth, of this Revelation.

Of the Heavenly City, tho' only the literal Truth endures

Its metaphoricity, on Hearts, yet Thy Ruth secures

In commenting on this verse, Prof Pritchett has listed others which contain 'snide remarks about Paradise' e.g.

kyā hī riẓvāñ se laṛāʾī hogī

ghar tirā ḳhuld meñ gar yād āyā

1) what a fight there'll be with Rizvan!
2) if your house, in Paradise, would come to mind/recollection

which paints a hilarious cartoon of Heaven's bouncer acting instead as a jailer.

Of course, the objective reality which this figurative speech alludes to is that of another figure of speech- in other words Ghalib is using a meta-metaphor- a very common one, whereby the visible delights of the beloved's house are enhanced by a metaphorical comparison to Paradise- of which we have only literal knowledge, not metaphorical understanding, through the unstinting Grace of Revelation.
Another verse Prof. Pritchett highlights is
satāyish-gar hai zāhid is qadar jis bāġh-e riẓvāñ kā
wo ik guldastah hai ham be-ḳhvudoñ ke t̤āq-e nisyāñ kā
That Garden of Rizvan of which the Ascetic is a praiser to such an extent/ it is a single/particular/unique bouquet in the niche of forgetfulness of us self-less ones. 
Here, the Ghalibian meta-metaphoricity arises from a deliberate semiotic slippage between collocations- e.g. sabz bagh and bagh e rizvan- such that Prof. Faruqi comments 'In this verse the beauty of style and rarity themselves are of no common order. To demean paradise with such a suitable word as 'bouquet', and then to do it in such a way that it is lower than the low and to make that very thing a cause of adornment (they arrange bouquets in niches) is no laughing matter. This is a high order of innate wit.... Then look at the use of 'self-lessness' with 'niche of forgetfulness'-- it creates a novel form of wordplay upon wordplay. When we've forgotten ourselves, why wouldn't we forget a commonplace bouquet like Paradise?....
It should also be kept in mind that 'niche of forgetfulness' is a metaphor; by using it in its dictionary meaning Ghalib has created a reversed metaphor. This too is a special trait of Mir and Ghalib's. (1989: 32-33) [2006: 42-43]'
A Meta-metaphor is, I think, a reversed metaphor; it is majazi majaz, it points to the phenomenal nature of phenomenal understanding- it is a Feurbachian thesis which prevents the semiotic slippage and degenerative moral indignation-as-Gadarening-availability-cascade Marxian brand of imbecility.
So Ghalib wasn't an atheist- either that or he was an atheist but not stupid. Since Indology can't admit that an Indian poet wasn't stupid, it follows that Ghalib was a true Muslim- if only by God's Grace.