Great thread!  I like the longer posts; they're thought-provoking and inspiring.

Like others, I've been through Catholicism, atheism, agnosticism, and Buddhism.  I pitch my tent at the junction of reason and awareness.  I tell people Boundary Waters trips are like a priest's going to church.  Makes 'em think.

As for God and being human, here's something to chew on.

Humans are (perhaps) unique in their ability - and need - to make meaning.  This is where God comes from.  God is a projection of human awareness.  We perceive the powerful workings of our own psyches, but we don't understand everything around us.  So we project the mystery outward and call it real (but just because you believe it doesn't make it so).

When I'm in the wilderness I'm tempted to credit God for its existence as well as my ability to appreciate it.  Then I realize that my experience of beauty - as well as my awareness that it's all so much greater than I am - is all in my head.  Certain spiritual people call this the coexistence of immanence (being in the here and now) and transcendence (going beyond the here and now).  It's wonderful to settle into that because then there's nothing between me and the world - no ideas, no theories, no spirituality - just the world, which happens to have me in it in this place and at this moment.

At such times I'm reminded of the words to a John Denver song:

Oh, I love the life around me.
I feel a part of everything I see,
And oh, I love the life within me.
A part of everything is here in me.

And that's where I stop thinking and just "be."

The wilderness experience is a kind of mental stretching, an attempt to expand my awareness to the point that I can let everything be "here in me."

God is so much easier, but this way is so much more real.

So, to the question of why I return year after year, I would answer simply that in this environment I am most able to set aside all that is artificial and connect with everything.  In this setting there are no boundaries but those I have not yet dissolved.