This is a very important statement in the novel. When Winston states that "we are the dead," it follows a statement that speaks more to Winston's above assertion. Winston insists that "She did not understand that there was no such thing as happiness, that the only victory lay in the far future, long after you were dead, that from the moment of declaring war on the Party it was better to think of yourself as a corpse." On the surface of it, it would seem that Winston, having decided to take on the Party, has already come to see himself as a corpse - perhaps not immediately, but soon, and it would be permanent. What efforts he and Julia make in their struggle against the Party will not bring about effect they themselves will enjoy. It is for later generations to see the benefits of their works.
Furthermore, from early on in the novel Winston realizes that being convicted of thought crime is tantamount to a death sentence (or vaporization sentence, I suppose). What he and Julia are contemplating will surely lead to their capture as thought criminals - which ultimately it does.
When taken into a larger context, however, "we are the dead" could reference the death of the individual self. That is, the death is not a physical death; it is a metaphorical death. All that defines them as individuals will be taken away, as it is through the process of O'Brien's interrogation of them in the Ministry of Love. In this sense, Winston's statement is a definite instance of foreshadowing. Winston and Julia (and the rest of society) are the dead...and the Party has killed them, or at least their will to individuality.
Because he basically realizes that everyone is the same, there is no uniqueness, they are all a bunch of zombies following orders from above, they are like machines easily replaceable and not really worth much, so therefore he concludes they are dead, lifeless, without uniqueness.
It probably means that everyone conforms now that there is no strain of indivisualism, that individuality is dead in that sense. Also it could mean that they are doomed to be discovered eventually if they commit an act of deference against the Party or a criminal act in the name of Law.
foreshadowing, check pg 230 where he repeats himself
"She did not understand that there was no such thing as happiness, that the only victory lay in the far future, long after you were dead, that from the moment of declaring war on the Party it was better to think of yourself as a corpse" (p.135) or (p.142).
By 'we are the dead' I think that winston is saying he know the thought police are eventually going to get him and kill him. He know that it is just a matter of time and that he is already marked to be 'the dead'.
Another reason for saying "we are the dead" may have something to do with his and Julias personalities, as they both think nothing like anyone else in their day and age. Their train of thought is how most people probably thought before the revolution with Big Brother. As most people that lived during the pre revolution are dead now, he refers to him and Julia as the dead. I'm pretty bad at explaining this sort of thing though so if anyone else got the same kind of read off of the quote feel free to jump in and say something.
From the beginning of the novel winston realises that thoughtcrime is death, he writes in his diary: "thought crime does not entail death, thought crime is death".
Winston thinks about the future, not only what it might look like but also what it might hold for him.
"We are the dead," is the first line in the second stanza of a war poem, written in the form of a rondeau, by Canadian physician, Lieutenant Colonel John McCrae. "In Flanders Fields" is one of the most popular and most quoted poems from WW1, and would be familiar to Orwell.
As a result of the poems immediate popularity, parts of the poem were used in propaganda efforts and appeals to recruit soldiers and raise money selling war bonds.
The poem is sometimes viewed as an anachronism; it spoke of glory and honour in a war that has since become synonymous with the futility of trench warfare, and the wholesale slaughter produced by twentieth century weaponry.
"1984" concerns itself, among other themes, with the rewriting of history for political ends. The poppy has become a wearable symbol, like the sash in "1984," to indicate patriotism, support of, and inclusion in, a society that worships perpetual warfare, whereas its origin was remembrance of needless sacrifice.
Compare the texts: The first (McCrae's) guarantees a future only through guilt, fear, and the perpetuation en masse, of the past (which can be re-written), and the second (Orwell's), which holds that the only possible future is through the individual, speaking truth.
"We are the Dead. Short days ago
We lived, felt dawn, saw sunset glow,
Loved and were loved, and now we lie
In Flanders fields.
Take up our quarrel with the foe:
To you from failing hands we throw
The torch; be yours to hold it high.
If ye break faith with us who die
We shall not sleep, though poppies grow
In Flanders fields."
“We are the dead. Our only true life is in the future. We shall take part in it as handfuls of dust and splinters of bone. But how far away that future may be, there is no knowing. It might be a thousand years. At present nothing is possible except to extend the area of sanity little by little. We cannot act collectively.
We can only spread our knowledge outwards from individual to individual, generation after generation. In the face of the Thought Police there is no other way.”