http://www.torah.org/learning/perceptions/5763/kiseitzei.htmlSEUDOS SHLISHIS:Remember what Amalek did to you along your way when you left Egypt. He confronted you on your way, and attacked the feeble stragglers who trailed behind you, while you were tired and exhausted. He did not fear G-d. Therefore, when G-d your G-d has given you rest from all your enemies around you in the land which G-d, your G-d gives to you as an inheritance, annihilate every trace of Amalek from under heaven. Do not forget this. (Devarim 25:17-19)The Vilna Gaon taught:
The principles that are the basis of the deeds to be performed at the beginning of the Redemption, and the circumstances and manners of these deeds are similar to those prevalent during the period leading to the construction of the Second Temple, consistent with the mission of Moshiach Ben Yosef. The beginning of the Redemption is the time of the Revealed End, when the following seven pillars are hewn: 1) gathering in the exiles; 2) building Jerusalem; 3) eradicating the impure spirit from Eretz Israel by planting the Holy Land and fulfilling the commandments related to it; 4) setting up people of truth in order to redeem the truth and sanctify the name of God; 5) promoting the spread of Torah from Tzion; 6) waging war against Amalek; and 7) healing Tzion. We, the emissaries of the Almighty, are obligated to do our utmost to carry out these goals . . . (Kol HaTor, Chapter 6)
Thus, there is no way around it: the path to the Final Redemption cuts across the formidable door step of Amalek, and the Vilna Gaon explains how in more detail:
The war against Amalek is in each generation, against three types of enemies: Amalek of the heart, that is, the evil inclination and vices; the spirit of Amalek, that is, the general one - the Satan, the adversary of Israel, who destroys. This is Samael and his hosts. His main power is in the gates of Jerusalem when its lands are desolate; the material Amalek, that comprises Eisav, Yishmael, and the Erev Rav . . . The strength and rulership of Amalek's spirit is in the gates of Jerusalem, as mentioned above, but only when there is destruction and desolation near the gates and in the unwalled areas of Jerusalem. As long as the spirit of impurity rules there, the feet of the cypress tree cannot stand there. This delays the connection between the Jerusalem of below and the Jerusalem of above - the connection between the Shechinah and Knesses Yisroel on which the entire Redemption depends. (Kol HaTor, Chapter 6)
Thus, there are three facets to the battle against Amalek. The first one is the yetzer hara. Amalek was not merely a people who once attacked us in the desert, in order to reduce our sense of spiritual invincibility. Amalek is a conceptual reality, and anything that cools down the heart of a Jew and takes advantage of his spiritual doubt is considered to be Amaleki in nature. This is why the numerical value of the word "Amalek" is doubt, because he causes it and takes advantage of it.
Then there is the aspect of Amalek that occupies the minds of men around the world, leading them to do that which destroys good in the world. This is a familiar concept and the topic of many a scary movie, but a real concept nevertheless. He is most powerful, in this aspect, when Eretz Yisroel remains uninhabited by Jews and undeveloped, particularly spiritual undeveloped. Thus, he is very much opposed, to say the least, to the giving of Eretz Yisroel to the Jews, and their development of it.
The third aspect of the battle against Amalek is the alliance that develops between the descendants of Edom, Yishmael, and the Erev Rav, which compromises just about the entire world. They are his tools to stop the return to Tzion, at least as long as he can, for he (they) cannot do so forever.
They have many weapons at their disposal, some physical, some spiritual, and we are witnessing them all today. Whether it is a suicide bomber, a political attack, or an overwhelming onslaught of Western materialism, the result is all the same. Tzion remains in ruins, with no real scheduled date of completion in the minds of Jews, at least while Amalek occupies the very hearts of the Jewish people.