It’s dated, called a fable; men are clever,
But they are just as badly off as ever:
The Evil One is gone, the evil ones remain.

[Er ist schon lang in Fabelbuch geschrieben;
Allein die Menschen sind nichts besser dran,
Den Bösen sind sie los, die Bösen sind geblieben.]

Johann Wolfgang von Goethe (1749-1832) German poet, statesman, scientist

Faust: a Tragedy [eine Tragödie], Part 1, sc. 9 “Witches’ Kitchen,” l. 2557ff [Mephistopheles] (1808-1829) [tr. Kaufmann (1961)]
    (Source)

On humanity no longer believing in "Satan."

Some translations (and this site) include the Declaration, Prelude on the Stage, and Prologue in Heaven as individual scenes; others do not, leading to their Part 1 scenes being numbered three lower.

(Source (German)). Alternate translations:

This many a day 'tis written down a fable;
Yet men are nowise winners in the game.
They're rid of the Evil One, the Evil still are able.
[tr. Latham (1790)]

That's been known as a fable many a season;
But men have things no better for that reason.
Free are they from the Evil One; the evil are still here.
[tr. Priest (1808)]

It has been long written in story books; but men are not the better for that; they are rid of the wicked one, the wicked have remained.
[tr. Hayward (1831)]

To fable-books it now doth appertain;
But people from the change have nothing won.
Rid of the evil one, the evil ones remain.
[tr. Swanwick (1850)]

It has long since to fable-books been banished;
But men are none the better for it; true,
The wicked one, but not the wicked ones, has vanished.
[tr. Brooks (1868)]

It's long been written in the Book of Fable;
Yet, therefore, no whit better men we see:
The Evil One has left, the evil ones are stable.
[tr. Taylor (1870)]

That name has had its station long assigned
With Mother Bunch; and yet I cannot see
Men are much better for the want of me.
The wicked one is gone, the wicked stay behind.
[tr. Blackie (1880)]

It's now a name for fairy tales and fables;
the people are as miserable as ever --
the Evil One is gone, the evil ones remain.
[tr. Salm (1962)]

It's been consigned to storybooks for youngsters;
Mind you, men are no better off for that.
The Fiend is gone, the fiends are still amongst us.
[tr. Arndt (1976)]

The name has been a myth too long.
Not that man's any better off -- the Evil One
They're rid of, evil is still going strong.
[tr. Luke (1987)]

Since God knows when it belongs to mythology,
But that's hardly improved the temper of humanity.
The Evil One's no more, evil ones more than ever.
[tr. Greenberg (1992)]

It only comes in fairy stories nowadays.
But even so, humanity's no better off --
The Evil One has gone, they've kept their evil ways.
[tr. Williams (1999)]

It’s written in story books, always:
Men are no better for it, though:
The Evil One’s gone: the evil stays.
[tr. Kline (2003)]