The irony of divine condemnation
The ironic endlessness of Sisyphus's doom suggests that as a symbol, it suits the ironic nature of human life and death. Camus points to the ironic poignancy and beauty of the system of futility that Sisyphus is condemned to, observing that, because of its eternal nature, the punishment ultimately demonstrates the perfect senselessness of it. Its unnecessary aspect is how Camus perceives the absurd nature of human life, which seems condemned like Sisyphus's life, to absurdity.
The ironic torture of senseless work
For Sisyphus himself, this irony is not as poignant as it is to mortal men who bear Sisyphus's burdens alongside him, but not immortally as he does. Eventually, every human dies, leading to an ironic emotional burden about wasted time. Sisyphus's torture points to the true torture of having wasted one's limited time on earth, especially by repeating daily jobs that feel senseless and meaningless.
The irony of meaninglessness
There is a tendency in human perception to look for patterns and layers of meaning, like looking at a foreign language and assuming because of the deliberate shaping of the letters that it means something. That is what Camus notices about the irony of meaninglessness. The world seems to imply meaning, but by looking for meaning within the world's systems, a person is doomed to existential nightmare and lonely suffering.
The irony of hopelessness
Technically, hopelessness is also an ironic response to the problem, which is doubly ironic, because it seems to make one want to feel hopeless, hearing that technically, everything is absurd and meaningless. There is no good, positivistic reason why one should believe any negative beliefs about reality, because meaninglessness also precludes that kind of hopelessness, logically speaking.
The irony of theology
Although the essayist invokes theological motifs, like divine punishment, for instance, the actual logic of the arguments is secularistic, because part of the meaning that Camus sees through with his logical skepticism is the meaning of human religions. If human life is absurd, then the religions of man are like the ironic petals on a flower of futility. He sees Sisyphus as a hero because he finds peace not in beliefs about a better tomorrow, but at the end of a day, when he gets to the transcendental bliss that ironically awaits him at the top of a mountain difficultly climbed. Camus's conception of God is that if there is a God, he's torturing us in ironic senseless ways, making the journey toward happiness a kind of fight to the death.
