Why are people so confused about the ending? Gotta be people just trolling at this point.
Everything we saw actually happened. Christian wrapped it up with a neat little bow at the end of the show:
Jack Shephard : Are you real?
Christian Shephard : I sure hope so. Yeah, I'm real. You're real. Everything that's happened to you is real. All those people in the church, they're all real too.
Jack Shephard : No. They're all... They're all dead. I'm dead. You're dead.
Christian Shephard : Everyone dies sometime, kiddo. Some of them before you, some... long after you.
Jack Shephard : But why are they all here now?
Christian Shephard : Well, there is no "now", here.
Jack Shephard : Where are we, Dad?
Christian Shephard : This is a place that you... that you all made together so that you could find one another. The most important part of your life was the time that you spent with these people on that island. That's why all of you are here. Nobody does it alone, Jack. You needed all of them, and they needed you.
Jack Shephard : For what?
Christian Shephard : To remember. And to... let go.
Jack Shephard : Kate... She said we were leaving.
Christian Shephard : Not leaving. No. Moving on.
Jack Shephard : Where are we going?
Christian Shephard : Let's go find out.
At this point I'm positive people are just trolling or simply paid absolutely zero attention when they "watched" the show. It couldn't be in plainer English.