BlueWing, here is an attempt at assimilating parts of your creed...and relating it to a slightly different endeavor than God, our life's pursuits. I feel the stuff you included about philosophers discussing man's ultimate unhappiness relating with the ideas of the noumenal, phenomenal, finite, unquantifiable etc ...could of lead to a very different conclusion.
(if my attempt at synthesizing is far off, then I would still like to hear what your thoughts are based on my conclusion derived from own interpretation, even if its not the interpretation you desired)
Humans are aware of how finite they are in their existence. Our observable time on earth is finite and everything we do is a finite action. Everything we create is only manipulating finite masses. We are confined to the empirical and finite. We find this idea limiting, and so seek such undefinable, unquantifiable and therefore SEEMINGLY INFINITE goals. These are therefore impossible objectives because they can't be ACCURATELY or RIGOROUSLY defined in the empirical world, such as love, spirituality, justice, immortality/infinite legacy, supreme power, etc.... These all ultimately fail because we all only have finite means of attempting to reach these unquantifiables. So in trying for love we can only find sex/time spent with someone. In search for immortality all Donald Trump can build is finite buildings. In search for power, all military conquerors could find, was finite amounts of land on a map.
So ultimately we come to find that finding a way out of being finite is futile. However, being finite, is not in of itself a happy realization. We arrive back at the idea of human existence being ultimately unhappy. So to be truly happy we really must not even exist. We have already "not existed" in seeming infinite amount of time, and will return to such a state. So to waste this blip of time, for a quicker return to that state is not worthwhile. That state will always be there, and the world we live in, no matter how unhappy, might as well be experienced. Staying here and experiencing here, in no way hinders how much time we will take away from nonexisting (infinity - 1 = infinity, the 1 is negligible). So we might as well exist and "enjoy" it.
The best we can arrive at: Rather than thinking about a pursuit of happiness, think of life as a pursuit of experience. Its the closest we can get to when discussing the merits of why one should exist in unhappiness rather than the happiness of unexistance. Also, why is it everyone is able to understand that two separate people are describing say God, love, justice etc, even though they can't accurately define or agree on a definition of these unquantifiables? I wager its because they are still brushing up on a bit of the truth, thus we are all aware of "how close" we are to defining the undefinable. In such a sense, living life as a pursuit of experience, besides being closest to the actual merits of existence, also may put us closest to "brushing up" on that bit of undefinable happiness.
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Slightly different twist, but borrows heavily on the stuff concerning: finite, unquantifiable etc... if i just butchered it all to hell, then oh well haha