A line from Dante's Divine Comedy:

{...}"Sweet spirit,

what souls are these who run through this black haze?"
And he to me: "These are the nearly soulless
whose lives concluded neither blame nor praise.

They are mixed here with that despicable corp
of angels who were neither for God nor Satan,
but only for themselves. The High Creator

scourged them from Heaven for its perfect beauty,
and Hell will not recieve them since the wicked
might feel some glory over them." And I:

"Master, what gnaws at them so hideously
their lamentation stuns the very air?"
"They have no hope of Death," he answered me,

"and in their blind and unattaining state
their miserable lives have sunk so low
that they must envy every other fate.

No word of them survives their living season.
Mercy and justice deny them even a name.
Let us not speak of them: look and pass on."

I saw a banner there upon the mist.
Circling and circling, it seemed to scorn all pause.
So it ran on, and still behind it pressed

a never-ending rout of souls in pain
I had not thought death had undone so many
as passed before me in that mournful train.

-Inferno, Canto 3, Lines 30-54. (Modern Library 1996, John Ciardi: Translator)

In The Divine Comedy by Dante Alighieri, Dante and Vergil visit the Vestibule of Hell, the final resting place of the opportunists. After passing under that gateway to hell, reading the inscription "Abandon all hope, ye who enter here," Dante states that he had not thought death had undone so many when speaking of the number of opportunists that he sees. This is a unique statement in all of the Divine Comedy, and implies that the number of souls here vastly outnumber the souls in all other places. Dante is saying that there are far more opportunists than fiends or righteous men. The vestibule of hell holds a harsher punishment than all the true circles of hell. The opportunists will not be ressurected at the apocalypse, and will never be granted paradise, repose, or even oblivion. This is the source of the common mis-quote attributed to Dante:

"The darkest places in hell are reserved for those who maintain neutrality in times of moral crisis"

Dante never explicitly made that statement, but has implied it in his Divine Comedy.