The show dealt with issues we all struggle with regardless of religious views - why are we here, what really matters, what happens after we die. Who doesn't think about those things?
The final 15 minutes was shown through Jack's POV. So it was framed by his beliefs, his worldview. I imagine the Kwan's saw or would have seen it very differently. Was it purgatory? Was it a metaphysical room between universes and time? Was the island rewarding the "good" people? Was the sideways time all just that brief moment between Jack's life and his death? Was it something Jacob set up? Or Jacob/Jack? or Jacob/Hugo? I don't know. I don't care.
In the end, the story of LOST, the story that Damon and Carlton decided to share with us, was about these people. I thought the final scenes said so much about community and the importance of the families that we create through circumstance and love.
I'm good with that.