That kind of “non-sense” is what physicist Sabine Hossenfelder sarcastically calls “Existential Physics”. — Gnomon
Pondering what is 'before the beginning' is just the kind of question that Buddhism designates as
unanswerable, of which in some versions, there are ten:
1. The world is eternal.
2. The world is not eternal.
3. The world is (spatially) infinite.
4. The world is not (spatially) infinite.
5. The being imbued with a life force [i.e. 'soul'] is identical with the body.
6. The being imbued with a life force is not identical with the body.
7. The Tathagata [i.e. the Buddha] exists after death.
8. The Tathagata does not exist after death.
9. The Tathagata both exists and does not exist after death.
10. The Tathagata neither exists nor does not exist after death.
Scholar T R V Murti notes in his 1955 book, The Central Philosophy of Buddhism, that there are considerable similarities between this list and Kant's antinomies of reason, particularly the first four. (The book contains many comparisions of Buddhist philosophy and Kant, for which it is nowadays mainly criticized.) The Buddhist attitude towards such imponderables is expressed by the 'simile of the poisoned arrow', in which a wanderer is shot by a poisoned arrow, but rather than seeking to have it removed, wants to know who fired it, what it was made of, etc, and consequently dies as a result. The Buddha's teaching is to 'remove the arrow', i.e. overcome the cankers and cravings, rather than think about unanswerable questions such as these.
(This is frequently interpreted to say that Buddhism is 'anti-metaphysical', but that is only partially true, as Buddhism is certainly not positivist or naturalist in the modern sense, although consideration of that would take us far afield.)
Closer to home, there's another way of framing the whole problem of 'before the beginning'. I think, perhaps, the idea of trying to envisage God as being a literal first cause in a series of events is itself problematical, as it is in a way reductive. It's part of the 'God as supreme engineer' metaphor. But I don't know if a first cause is conceptually equivalent to the 'ground of being' in philosophical theology. It is more like the hypothesis that LaPlace had no need of. Karen Armstrong's 2009 book, The Case for God, laments that this tendency of early modern science to hypothesis God as standing behind science, as one of the causes of the decline of faith in God. Her view is that the basis of religious cosmologies resides in a fundamenal cognitive shift on the part of the believer, not in a theory of everything (
review.)
One further remark - George Lemaître himself was a Catholic priest, but he never invoked his cosmological theories as any kind of argument for God. In fact by the 1950's, Pope Pius XII had started to mention Big Bang theory as a kind of affirmation of 'creation ex nihilo' - something which embarrased Lemaître, as he believed that his scientific work was a separate matter to his faith, and who prevailed upon the Pope's science adviser to, you know, cool it. Which the Pope did! He henceforth refrained from making such a connection in his speeches. A salutary lesson, I would have thought.