If one were to trace his lineage and find that he is from the line of the great King David, would he not be thrilled at such a tremendous genealogy? Would he not think of all the vast inherent potential, the awesome capacities to reach soaring spiritual heights? Or would he go one step further and see that such a lineage actually traces itself to the awfully immoral society of Sodom and Gomorra, the archetype of malevolence and selfishness? What is Hashem revealing to us that the Mashiach comes from such a society?
In this Parasha of Maatos (staves) Hashem tells Moshe to kill the men and women of Midyan while leaving the betulot (virgins) alive. It is quite peculiar that Hashem limits to Midyan the command to exact vengeance for the horrible sin committed by Midyan and Moav; for Moav was equally guilty for bringing the children of Israel to sin at Peor! Yet somehow at this stage in the game the nation of Moav and the betulot of Midyan are to be kept alive. Why?
On the Pasuk in Dvarim (23:4) stating that a Moabite and an Ammonite cannot become members of Bnei Yisrael because they did not greet us with bread and water, Chazal explain that the Pasuk is referring to a Moabite man and not a woman. How can this be? If the women were guilty of seducing the men of Israel - should they be able to convert and not the men? Rather, the depth is this: the lust of Moav manifest in the women can and must be channeled for good; but the lack of mentchlichkite and sensitivity displayed by the Moabite men cannot. Since the same is true for the nation of Midyan, why is it that Midyan is to be attacked and not Moav? Because the process of sifting out and redeeming the divine sparks in Midyan has already been fulfilled through Moshe via his marriage to a Midyanite woman, while David has yet to come from Moav (interestingly enough, Moshe is commanded to wreak vengeance against Midyan, and while David does the same to Moav - perhaps the purged elements must complete their purification via destroying the their now irredeemable source?)
This raw potential of the women of Moav is precisely the reason why they are kept alive - to sift and to channel this chiyus (life force) positively. The same is true for the betulot of Midyan; since they are still pure (having not "known" a man), their potential is still untainted. Hashem is telling Moshe not to walk away from, but rather to utilize positively that which has the capacity for good.
This idea is expressed even stronger in the detailed description of how a significant portion of the loot of Midyan is given to the Tabernacle - for all these elements can be purified and used for holiness.
Is there anything more powerful than this? A person often may so be downcast due to repeatedly falling into the unholy thinking that he is certain he has no possibility to reach the wonderful realms of spirituality and holiness. And as hard as he struggles, he cannot totally rid himself of bad traits because they seem to linger on. But on the deeper level, there is ultimately nothing truly bad or unholy; everything comes from one source of good from G-d. It is not to escape or liberate oneself from lust, rather to use that force positively, by sifting out and positively applying its untainted root. The same person whose heart was burning for immorality takes that fire to intensely yearn for G-d. Hashem did not create evil, He created potential. Where was the root of all the intense lusts? Where was it all coming from? From the shoresh of tov.
The Mashiach comes from Yehuda being with a zona, from Lot's daughters being with their father, from the things that the Torah says are completely wrong and anti-holy. The depth of life is that all which a person views as bad and wrong is only a mistake on his part. I can see Sodom and Gomorra or I can see King David. I can see the sins of Midyan or I can see the potential within those sins. I can see all my mistakes as irretrievable things of the past or I can use them to create my future for good (as Chazal say that when a person does Tshuva from love of Hashem, his sins become merits). When a person matures in his Avodas Hashem, he sees his every desire as a pining for G-d. He experiences certain drives towards the "unholy" and "wrong" and uses that chiyus to leap into learning with real excitement, to daven in a fire of longing for G-d. He begins to notice everything as an opportunity and not as a problem.
This is not only true on a personal level, but also on a universal level. David writes in Tehillim that when Hashem returns to Zion, our mouths will be filled with laughter and our tongues with joyous song; all that was seen as bad will suddenly and surprisingly be seen as a good we could not fathom - this juxtaposition will generate a profound laughter and a staggeringly spontaneous song. All of a sudden the sight of one root of good becomes clear to the whole world. May we merit this vision of Avraham who sees David hidden within Moav and the return of Hashem to Zion soon speedily in our days. AMEN!!
( based what I gleaned from Shiurim I heard from R' Amos Luban and R' Aharon Lopiansky)