I had a difficult time deciding if this movie should get 2 or 8 stars

Rating: 3/10 (31 March 2009)

Evaluating this movie is, for me, rather difficult. If a movie is to be judged only on what transpires from the opening to closing credits, I would be willing to have given "Knowing" perhaps six or seven stars. The seven stars would come from a great beginning, a nifty sort of mystery that unfolded at a reasonable pace--and then an ending that was horrible not so much because of the calamity factor but because it completely nullified the entire point of the preceding part of the movie.
I am beginning to become convinced that for a movie to rate more than five stars it has to give the viewer something more than two hours of diversion. Such a movie should give the viewers something to think about or relate to their own life or ponder "What would I do in this situation", and so on.
THE REST OF THIS REVIEW IS RIFE WITH ***SPOILERS*** How to deal with the death of a spouse, maintaining a healthy, single-parent relationship with a son, or even "What would I do if my child brought home a cryptic 50-year-old message" can draw an audience in and, in fact, this part of the movie was well done. But the ending nullified all of this and, in fact, gave the first 9/10 of the movie all the meaning of a mouse running in one of those circular treadmills. All his (Nicholas Cage's) running around, getting involved in two disasters--even his rescuing of a few people from a plane crash was, by the end of the movie-and-world, completely pointless. Even his dramatic reading of the fingernail-scratched door was important only after one takes a "suspend belief pill" that will allow the viewer to accept the fact that only way a super-powerful alien race can rescue two children is to assume that the kids will be at a certain place at a certain time--as described in old scratchings on a door.
The other thing that bothered me was the lack of logic. Here are some examples: The "aliens" seem to know our future--including the "end of the world" calamity. They knew 50 YEARS (at least) in advance that a solar flare was going to scour all life from the earth. They had tremendous powers. Did they use that power to build (or have us Terrans build) some sort of solar flare shield? Did they decide to evacuate as many people as they could during that 50 years? No. They decided to rescue two (or, perhaps, a few more) children that had not even been born yet.
Why did they "call" (i.e., rescue) only children? And only a few of them, at that.
The whole movie was based on the message from 1959. But it ultimately had no point whatsoever. By suspending lots of belief, it could have been for the purpose of getting two children to the space craft pickup point. But even there it was not relevant--the aliens DROVE the children to the proper place.
Why did they say "no" to the father of one of the children? For that matter, why did they say "OK" to a pair of rabbits? (After five years, the rabbits probably outnumbered people on the new world about ten million to one.) Why the drama about the pebbles around the pickup point? They (but not dirt, etc.) seemed to be affected by the space craft's propulsion but they otherwise did nothing.
The movie had a great premise and (until near the end) continuing interest. My feeling while walking out of the theater--and now, a few days later--was like I watched an exciting football game. Then all the players were shot.