This is chalked up as ireverent because if there is no metaphysical obligation then our own consciousness and free-will, as a fundamental quality, takes the place of metaphysical obligation. In short,

“If nothing we do matters, then the only thing that matters is what we do.”Angel TV Series (https://www.youtube.com/watch?v=2gXaMnkmGq0)

• https://www.reddit.com/r/ANGEL/comments/1mjzsl/discussion_of_angels_statement_if_nothing_we_do/
• https://www.quora.com/Which-philosophy-is-this-closest-to-If-nothing-we-do-in-this-world-matters-then-the-only-thing-that-matters-is-what-we-do

The issue itself is discussed literally everywhere and could be considered a fundamental lesson of Philosophy 101.

It always reminds me of his conversation with Buffy in 'Gingerbread' (BtVS S3:E11), when Buffy's mom has her questioning whether being the Slayer means anything or if it really is fruitless.

Angel: Buffy, you know I'm still figuring things out. There's a lot I don't understand. I do know it's important to keep fighting. I learned that from you.

Buffy: But we never…

Angel: …never win.

Buffy: Not completely.

Angel: Never will. That's not why we fight. We do it cause there are things worth fighting for.Buffy the Vampire Slayer S3:E11 'Gingerbread'

The idea that these can be pulled out of popular culture TV shows shows the absurdity of holding the position as an artifact of arguing out of a lack of philosophical or religious wisdom.

Also see: Falsification of Atheism.

1. Nothing we do matters.
2. What we do matters.

That 2 follows from the premise is self-evident because we deem our own observation and conclusion as a valid observation. Therefore the actions that we choose to do are assumed to be moral and right in and of themselves; in essence, 2 is the disproof of 1 in a sense, while also following from it; or rather 2 is the obvious response to 1, which is uttered after realizing it is self-evidently false. No proof needs to be brought – you're supposed to know because, you know things.