My daughter just asked me to listen to this song, and wow! I can see why. This is an amazing song. Since I know nothing of this band and it's the first time I heard the song, my impression in trying to figure out the meaning was that it's a person who's never really felt quite "at home" anywhere. Maybe growing up, there was a bad situation and/or they felt very different in personality from other family members, hence feeling "this isn't quite 'home' for me". And then, after moving out, realizing that they haven't yet found a place or life that they can "call home", and wondering if they ever will. As for the "heaven won't let me in" part, I too, see that as some others have said that it's someone who knows they're not living the life they should, so "heaven won't let them in", yet they're not ready or they're unwilling to change, yet at the same time are still somewhat sad about it somewhere deep inside.