In Goethe's Faust, why does God allow Mephistopheles to tempt Faust?
In Goethe's Faust, in the "Prologue in Heaven," the Lord is in heaven, gathered with his heavenly host. Included among those there are the angels, Raphael, Gabriel and Michael; Mephistopheles is also present.
Each of the angels praises The Lord's creation, including the sun, the oceans and even the power of thunder and lightning storms. Since the primal (first) day of the world, all of The Lord's good works are as glorious and beautiful as they were on that first day.
Mephistopheles (Mephisto), claims that he has no words of praise for the sun or the ocean. He complains, instead, that since mankind saw the first glimmer of heaven in the knowledge they received in the Garden of Eden, they have been miserable.
You’ll get no word of suns and worlds from me.
How men torment themselves is all I see.
The little god of Earth sticks to the same old way,
And is as strange as on that very first day.
He might appreciate life a little more: he might,
If you hadn’t lent him a gleam of Heavenly light:
He calls it Reason, but only uses it
To be more a beast than any beast as yet.
Mephisto's complaint is that rather than rising above the animals with that "gleam of Heavenly light," they act more like beasts every day. Mephisto, therefore, has no praise of The Lord or his works at all, only criticism.
The Lord asks whether he comes always "thus, with ill intention?" Does nothing go "right on earth"? But Mephistopheles complains that it is so bad, not even he wants to visit there anymore.
The Lord has great faith in one man in particular, and so he draws Mephisto's attention to Doctor Faust. (This part of the plot is very similar to Satan's temptation of Job in the Old Testament of the Bible.) The Lord says he may be a doctor, but he is The Lord's servant first. To prove that Mephisto is wrong about mankind, The Lord permits Mephisto to tempt Faust as long as he is alive. The Lord is certain, though, that by the end of his life, he will still be his faithful servant. Faust may be having doubts now and making mistakes, but he will come around: as long as he lives, at least he is still trying: mistakes are part of living.
For while man strives he errs.
So, in essence, the temptation of Faust is Goethe's description—in this literary piece—of how man is tempted every day of his life, choosing between The Lord and "darker powers." In this piece, Goethe presents the situation as a wager between The Lord and Mephistopheles. The Lord does not doubt Faust, and the wager is on so The Lord can convince Mephisto that humankind is inherently good, despite the temptations that come his way; The Lord believes Faust will remain faithful and learn some important lessons on the way. The Lord predicts what Mephistopheles will find:
And when you must, then stand, amazed:
A good man, in his darkest yearning,
Is still aware of virtue’s ways.
When Heaven closes, Mephistopheles comments on what a gentleman The Lord is:
I like to hear the Old Man’s words, from time to time,
And take care, when I’m with him, not to spew.
It’s very nice when such a great Gentleman,
Chats with the devil, in ways so human, too!