So I actually think the 'alive' model is perfectly valid by the definition of life I learned. It really applies to the biosphere and not 'the planet', though, which is a screwy bit of language sometimes. Colonizing Mars is a totally valid incidence of reproduction of our biosphere, and I'm sure the bacteria in your digestive tract have their own opinions on marshmallows, or in my case, cheap beer (no I am not assigning any necessary degree of intelligence or emotional capacity to bacteria just using a word in a stretched situation). Likewise, I take all the water out of you and launch it into space and it'll keep right on being water. Or you can take the rocks out of a bird's gullet for the same effect.
I think the problem is more that someone sometime was like 'hey guys, wtf is life?' and then someone else was like 'dude look at this list of approximately seven things, that seems like a sensible definition of life amirite?' and now somebody else is like 'lol your definition applies to the everythings everywheres' and some other people are like 'fuuuuuuuuuuuuckkkk yoooouuuuu'.
What I mean to say is, those 'defining characteristics of life' are just a list of things we came up with to try and categorize 'life', life, of course, being a word that is full of all sorts of other connotations in language. We have written up a list of things, and found things that fit all the things in that list. We have done nothing more and nothing less, and if we use that list as a definition of a word, then the word fits, but nothing else has been ascribed based on that definition.
Yes, the biosphere is alive and can be modeled as a single living thing. No, I do not believe it has a soul or a spirit any more than I believe the seeds in my garden, my neighbour's dog, or my dead loved ones have or had a soul.
I think it is dangerous to take a 'scientific' definition of life to be anything other than exactly what it is.
The example I keep coming back too is the Gaea hypothesis, the idea that the biosphere of planet Earth is a living thing unto itself. There is no way to approach this idea using the scientific method. No test or measurement we could apply would conclusively tell us that the biosphere is a unified and living thing or isn't. It's a question of what model we use to envision the biosphere, and from the point of view of the scientific method, it's an arbitrary and effectively meaningless distinction because it's a question with no testable or provable answer. I happen to think it's extremely important for humans to start thinking of the Earth as a living thing, so I have an issue with a society that depends on the scientific method as an arbiter of truth to the extent that it sees this question as meaningless.
See, I like the idea of thinking of the earth as a living thing, it's a neat concept and is useful for helping us think about our actions, but I think it's silly to get carried away with it. I also find your claim that no test can tell us this thing to be a little stupid. We just haven't designed a test. If the thing exists and has an effect on us, there must be a way to observe its effects. If there are no effects to observe, then it effectively doesn't exist. If we can't observe it's effects yet, hopefully we will be clever enough to do so later.