Shabbat Zachor is one of the four special Sabbaths that occur before or during the month of Adar or Adar II in leap years.
On Shabbat Zachor, the Sabbath before Purim, we read Deuteronomy 25:17-19, which mentions the commandment to remember and exterminate the evil of Amalek and his memory.
The special Haftarah reading for Shabbat Zachor is 1 Samuel 15:2-34 which speaks of God's command to King Saul to destroy the Amalekites. This reading was chosen because Haman of the Purim story was a descendant of Amalek.
Exodus 17:16 tells us that God is at war with Amalek for all generations. This war is seen not so much as a physical war in our day and age but rather a spiritual war. The weapons we use in the war of Amalek are those of the whole armor of God:
For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand firm. Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, and, as shoes for your feet, having put on the readiness given by the gospel of peace. In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one; and take the helmet of salvation, and the sword of the Spirit, which is the word of God, praying at all times in the Spirit, with all prayer and supplication. Ephesians 6:12-18
Amalek represents a negative sense of doubt. This is based upon the verse in Exodus 17 where the children of Israel said, "Is God among us or not?" After they experienced doubt, the text says, "Then Amalek came and attacked Israel in Rephidim." The numerical value of the Hebrew for Amalek is the same as that of "doubts," 240. Amalek also represents pure hatred, as it says, "And he did not fear God." The classic Torah commentator Rashi says regarding this verse, "Amalek did not fear God [so as to refrain] from doing you harm" (quoting the Sifre).
In a sense Amalek challenged God and truth. The evil inclination inside each of us challenges us; there is a constant battle being waged inside of everyone that beckons us to question the ways of God and thus rebel against Him. Note the words of Paul in Romans 7:22-23 for an elaboration on this war. This spirit of Amalek attacks when we do not have our guard up in the fight against evil in our day-to-day life, as it says, "When you were weary and exhausted and he did not fear God" (Deuteronomy 25:18). However, on Shabbat we are more closely connected to God because we are no longer distracted by the fears and worries of everyday life. Therefore, we are able to eliminate the Amalek inside of us on this auspicious day. This is seen in the similarities between the two commandments "Remember the Sabbath" (Exodus 20:8) and "Remember what Amalek did to you" (Deuteronomy 25:17).
The one who will finally eliminate the memory of Amalek from the earth is our righteous Messiah of whom it says, "From his mouth comes a sharp sword with which to strike down the nations, and he will rule them with a rod of iron. He will tread the winepress of the fury of the wrath of God the Almighty" (Revelation 19:15).
We should all strive to eliminate the Amalek inside us, as it says, "Put on the Lord Yeshua Messiah, and make no provision for the flesh in regard to its lusts" (Romans 13:14 NASB). "For though we walk in the flesh, we are not waging war according to the flesh. For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds. We destroy arguments and every lofty opinion raised against the knowledge of God, and take every thought captive to obey Christ, being ready to punish every disobedience, when your obedience is complete" (2 Corinthians 10:3-6).
As we draw near to the Passover season, let us all resolve to destroy the spirit of Amalek that wages war inside of us and "to present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship. Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect" (Romans 12:1-2).