Most of the most creative individuals, including geniuses, of the 19th and early 20th century were raised as Christians or as Jews - and most of these lapsed from the faith of their birth, to a greater or lesser extent: many indeed became atheists.
However, usually, their faith and energy (often, a furious energy) was instead channelled into their 'work' - they made 'a religion' of their philosophy, literature, critique, music, visual art, science... The results were often astonishing.
There were these titanic characters whose own struggles felt to them (and to those who were under their spell) as the struggle for purpose, meaning, reality itself... And this was, in fact, true - because by abandoning their birth religion they became dependent on their art or science or scholarship for everything which religion had previously given them.
There was often an anger and aggression about the creativity of these titans - they were (and knew this) holding back chaos, ordering reality by their own efforts - there was no safety net under them, but instead a void. They did not despair - but they knew themselves to be a whisker away from despair - hope being held-together only by their own creative efforts.
Of course the pride was immense - however, so was the achievement and the heroism.
But this was only possible for the first generation - for those who were brought up really believing the orthodoxy of their faiths and the need for belief; and whose apostasy was a personal act and against the expectations and in the face of criticism and persecution - not, as with later generations, following a trend, dragged along by the general flow, nor persuaded by the reflex radicalism of the mass media.
The later creatives were even more secular than their great progenitors; but they were not great - they were not really serious, because their work did not seem to themselves to be so important; they were not doing the work of religion because they did not acknowledge that this work needed to be done -- the later creatives were were laid back, cool, playful, ironic, amusing... maybe they acted-up a bit of anger or intensity, but it came across as spiteful and petulant rather than heroic because - after all - what was there to be heroic about?...
Religion was gone, and seemingly didn't need to be replaced. After all, the world hadn't ended...
The earlier geniuses had failed - they had not held back chaos, they had not kept later generations suspended above the void. The later generations were living inside chaos and the void, and they found it to be purposeless, meaningless, unreal - and with no possibility of ever becoming anything otherwise...
Thus we despair.