The parallel is fascinating and worth exploring.
According to David Hume, "Whatever we conceive as existent, we can also conceive as non-existent." (Dialogues Concerning Natural Religion) I've long believed Hume to be right about this. I would put it this way, trading Latin for plain Anglo-Saxon: Our minds are necessarily such that, no matter what we think of as existing, we can just as easily think of as not existing. This includes God. Now God, to be divine, must be a necessary being, indeed a necessary concretum. (God cannot be an abstract entity.) Therefore, even a necessary being such as God is conceivable or thinkable as nonexistent.
Try it for yourself. Think of God together with all his omni-attributes and then think of God as not existing. Our atheist pals have no trouble on this score. The nonexistence of God is thinkable without logical contradiction.*
Note the ambiguity of 'conceivable.' It could mean thinkable, or it could mean thinkable without (internal) logical contradiction. Round squares are conceivable in the first sense but not in the second. If round squares were in no sense conceivable, how could we think about them and pronounce them broadly logically impossible? Think about it!
Now try the experiment with an abstract necessary being such as the number 7 or the proposition *7 is prime.* Nominalists have no trouble conceiving the nonexistence of such Platonica, and surely we who are not nominalists can understand their point of view. In short, absolutely everything can be thought of, without logical contradiction, as not existing.
Humius vindicatus est.
I now define the sense of contingency as the sense that everything is thinkable without logical contradiction as nonexistent. I claim that this sense is essential to the type of mind we have. I also claim that the sense of contingency does not entail that everything is modally contingent, i.e., existent in some but not all metaphysically (broadly logically) possible worlds. So from the mere fact that I can think the nonexistence of God without logical contradiction, it does not follow that God is a contingent being. I further claim that we have a hard-to-resist tendency to conflate illicitly the sense of contingency (precisely as I have just defined it) with genuine modal contingency.
So, if someone argues a contingentia mundi to God as causa prima, he can expect the knee-jerk response: what caused God? Behind that reflexive question is the sense of contingency: if the universe is contingent (because conceivably nonexistent) and needs a cause, then so is anything posited as first cause. What then caused the First Cause? If nothing caused it, the knee-jerk responder continues, then it just exists as a matter of brute fact; and if we can accept brute-factuality at the level of the First Cause, then we can accept it at the level of the universe and be done with this nonsense. We can say, with Russell, that the universe just exists and that's all.
My point is that it is the sense of contingency, together with the illicit conflation just mentioned, that fuels the knee-jerk response to the argument to a causa prima.
The sense of absurdity as described by Thomas Nagel is analogous to the sense of contingency, or so I claim. The sense that our lives are Nagel-absurd does not entail that they are objectively absurd. And yet we are necessarily such that we cannot avoid the sense of Nagel-absurdity. About absolutely everything we can ask: what is the purpose of it? What is it good for? What is the point of it? The subjectively serious, under the aspect of eternity, viewed wth detachment from nowhere, comes to appear objectively gratuitous. This holds for every context of meaning, no matter how wide, including the ultimate context. Suppose the ultimate context is eternal fellowship with God. Reflecting on it from our present perspective, viewing it from outside, we can ask what the point of it would be, just as we can ask what caused God.
The classical answer to 'What caused God?' is that God is a necessary being. He has no external cause or explanation, but his existence is not a brute fact either. God is self-existent or self-grounding or self-explanatory. Nagel has trouble with this idea: "But it's very hard to understand how there could be such a thing." (WDIAM, 99) Why does our man have trouble? Because there is nothing that could put a stop to our explanation-seeking 'Why?' questions. In a sense he is right. The structure of our finite discursive intellects makes it impossible to stop definitively, makes it impossible to have self-evident, question-squelching, positive insight into the absolute metaphysical necessity of God's existence in the way have self-evident positive insight into the impossibility of round squares or the necessity of colors being extended. The best we can do is see the failure of entailment from 'Everything is conceivably nonexistent' to 'Everything is modally contingent.'
Just as Nagel cannot suppress the question 'What explains God?,' he cannot suppress the question 'What is the point of God?' or 'What is the point of fulfilling God's purpose for our lives?' Nagel cannot see how there could be something that gives point to everything else by encompassing it, but has no external point itself. He cannot see how God can be self-purposing, i.e., without external purpose but also not purposeless. Nagel thinks that if the point of our lives is supplied by a pointless God, and a pointless God is acceptable, then we ought to find pointless lives acceptable.
Nagel can't see how the ultimate point could be God or eternal life with God. "Something whose point cannot be questioned from outside because there is no outside?" (100) Given the very structure of our embodied awareness, there is always the possibility of the 'outside view' which then collides with the situated subjective 'inside view.' It is this unavoidable duality within finite embodied consciousness, and essential to it, that makes it impossible for Nagel to accept a self-purposing, self-significant, self-intelligible ultimate context.
So for Nagel objective meaninglessness is the last word. For me it is not: our lives are ultimately and objectively meaningful. But Nagel has a point: we cannot, given the present configuration of finite, discursive, embodied awareness, truly understand with positive insight God's metaphysical necessity or how there could be an ultimate context of existential meaning that is self-grounding axiologically, teleologically, and ontologically.
So I suggest that ultimate felicity and ultimate meaningfulness can be had only by a transfiguration and transformation of our 'present' type of finite, discursive consciousness with its built-in duality of the subjective and the objective.
But I can only gesture in the direction of that Transfiguration. I cannot present it to you while we inhabit the discursive plane. All I can do is point to the Transdiscursive, and motivate the pointing by exfoliating the antinomies and aporiai that remain insoluble this side of the Great Divide.
*One way to oppose this is via the Anderson-Welty argument lately examined. If the exsistence of God is the ultimate presupposition of the laws of logic, then all reasoning, whether valid or invalid, to God or away from God or neither, and all considerations anent logical possibility, necessity, impossibility, contradiction and the like presuppose the existence of God.
A second way of opposition was tread by me in my A Paradigm Theory of Existence.