Why does Jack tell Kate that they have to return to the island?!

Why does Jack tell Kate that they have to return to the island?

We're stationed in germany so "Lost" episodes dont come on for days after it is shown in the states.

^The ending is actually a flash forward, I'm giving you a link below, I hope it works in Germany and you can watch Lost. I got this from another website, but it basiclly sums it up. Enjoy.

I loved it. I picked up immediately that it was a fast-forward situation with Jack in a full beard, all gone to hell and hooked on pills, discovering he couldn't live life off the island. That's right, off the island. It was a great twist and a good tease to a series that has been a lot more assured the last month or so and began moving with real confidence. Last night there was an assured swagger to the finale. Not only was the pace fast, the teases taut, and the answers plenty, the writers took a compelling gamble (though one not too difficult to unravel or further complicate). They told viewers that in the future, all (or maybe all) of the people on the "Lost" island get off. They get their wish. But in Jack, our guide through this series, the writers definitively say, "Be careful what you wish for."

Again, it can't be said enough that this is a series that at least tries, it swings the bat. After meandering a bit and getting spanked for it, "Lost" has been one very motivated series. The question, though, is was this finale a good idea? We know they get off the island (or, just to be safe, that SOME of them get off). How much drama does that suck out of the coming seasons? I'm willing to bet that there's plenty of smart ways to tweak the drama and keep fans captivated. So don't sweat it.

Getting off the island, as seen through the looking glass, was the major twist. But Charlie also died - with some dignity, no less. (Of course, I'm not totally convinced he had to go out that way. If he could get to the hatch door before Desmond - and trying to save Desmond seemed to be the point - couldn't he have just closed it from the other side? Weren't there enough wet suits? And let's say that a grenade CAN explode underwater, because I guess that makes some sense, didn't Charlie think both he and Desmond could withstand the blast and get out alive? Would the substation fill up that fast? Just thinking out loud here.) Oh, a lot of Others got all blowed up. That was fun. Hurley ran some dude down in a VW Van. Jack beat the bejesus out of Ben, which was loooooong overdue. Rousseau and Alex were united and tied up dear old dad. Penny's still out there (which hopefully means more Desmond next season, brother). Walt showed up (and growed up). Locke couldn't walk, then could walk. In the future, someone is in a casket and nobody shows up for the funeral. Who is it? Oh, much happened. (And yes I used blowed and growed in this paragraph on purpose.) Much happened indeed.

"Lost" returns in January of 2008. I'm actually all for that. No reruns