Stop.
Occam time.

What Stephen was talking about was that life exists, but no mechanism insinuating a 'vital spark' can be seen.

Occam's razor, right? We posit that
A: There is nothing special about 'living' matter*, it's just bloody unlikely to form spontaneously.
B: There is a 'vital spark', something which separates non-living matter from living matter, but living matter can transmute non-living matter into living matter during the process of replication. Also, the vital spark is undetectable, but totally there.

So, you are positing an extra agency (vital spark) that isn't required to explain anything at all. Simpler explanation is better, because this is SCIENCE!

*Insomuch as it's organic material that self-replicates.

: Our own
: terminology for matter includes this separation of life and non-life.

...
What does that prove?
A trick of the english language? A bias in human cognition?

: Just
: because that separation hasn't been explicitly defined doesn't mean it
: doesn't exist.

You can't even begin to state what that separation is!

: We observe the difference, we just haven't been able to
: explain it (let alone prove there is no difference).

The default is that there is no difference. You have to prove otherwise.