There is a most fascinating halacha mentioned in this week's parsha with regard to tzora'as. Even a small patch of tzora'as has the ability to cause a person to become tamei. Yet, if the tzora'as spreads to the entire body and covers the person from head to toe, the Torah tells us that the person is tahor (see Vayikra 13, 13).
While it seems that this is an unexplainable spiritual law, it is clear from the Chazal that we can extrapolate from this concept to other areas of life. The Gemara (Sanhedrin 97a) states, "Said Rebbi Yitzchok, 'Moshiach will not arrive until the entire government turns to heresy.' Said Rava, 'Where is this mentioned in the Torah? The entire [affliction of tzora'as] has turned white; it is pure.'" When the entire government turns immoral, one can be sure that purity (i.e. Moshiach) is on its way. How are we to understand this concept which seems to conflict with logic? How can it be that the worse something gets, the better it really is?
Rav Wolbe (Ma'amarei Yemei Ratzon pg. 443) explains as follows. We relate to good and evil as two entities but with different values. Good is positive while evil is negative. However, it is clear that the Torah does not relate to evil in the same that we do. In many places the Torah equates good with life and evil with death. The Torah views good as a reality while evil is something which is not real at all. As we perceive the world today, it is hard for us to digest such a concept. Evil seems to be all too much of a reality, greatly overshadowing the good which seems to pale in comparison. It takes a perceptive eye to be able to discern the truth behind this façade.
When the spies returned from scouting out the Land of Israel, they prefaced their negative appraisal of the land with some positive aspects. "We have seen the land and indeed it flows with milk and honey" (Bamidbar 13, 27). Rashi tells us that they deliberately added some truth to their false account because, "A falsehood cannot endure unless it begins with a little bit of truth." Evil has no continuation unless it attaches itself to good. Every regime places either freedom or justice on their ideological banner because it is this virtuous aspect which gives them some degree of continuity. Consequently, when that aspect of good is lacking, the entire ideology crumbles along with the regime, because evil by itself has no continuity.
Thus, Chazal tell us that when the entire government turns to heresy, Moshiach will come. It was the minute amount of emunah that gave their regime its foundation, and when they lose that last bit of emunah the government will automatically self destruct, making way for the ultimate dominion of Moshiach. Rava finds proof for this concept from the halacha that when tzora'as covers the entire body it is tahor. Impurity cannot exist unless there is some purity for it to latch onto.
With this in mind, we can begin to understand the Ba'al Teshuvah movement of the past few decades. When ideologies lose any semblance of righteousness and crumble one after another, people begin to realize that all that is left is the truth and immortality of the Torah.
This is the key to understanding the Torah's guarantee that Klal Yisrael will do teshuva in the end of days (see Devarim 30, 1). When society loses all its morals, the glamour of the outside world crumbles and the truth shines in all its glory thereby bringing people to teshuva. We have definitely reached that point. The outside world has absolutely no morals, and they also have nothing positive to show for this permissiveness. The only absolute truth is the Torah and only it has the ability to bring us true fulfillment and serenity!