Chasidic thought explains that Amalek is a particularly dangerous enemy of the Jewish people, because the opposition to the Torah which Amalek represents is subtle and indirect, and thus does not appear to be contrary to Torah.
Amalek’s second attack (21:1-3)
Why, in their second attack, did Amalek come disguised as Cana’anites (see Classic Questions), whereas in their first attack (Shemos 17:18)they did not attempt to conceal their identity?
Chasidic thought explains that Amalek is a particularly dangerous enemy of the Jewish people, because the opposition to the Torah which Amalek represents is subtle and indirect, and thus does not appear to be contrary to Torah. Sympathy with the ideology of Amalek can thus set a person on a “slippery slope,” eventually leading him away from the Torah altogether, God forbid (see commentaries to Shemos17:8-16 and Devarim25:17-19).
On each of the two occasions mentioned in the Chumash that Amalek attacked the Jewish people their goal was different, and this was reflected in their mode of attack:
When Amalek attacked in Parshas Beshalach, the Jewish people were living a desert life of isolation and spirituality, representing our acts of Torah study and prayer that occur inside the study hall and synagogue. But in our Parsha, when Amalek attacked for the second time, the Jewish people had completed forty years of isolation in the desert and were about to begin their conquest of the Land of Cana’an —representing the challenge of maintaining our Judaism in the workplace and the marketplace.
Thus, during their first attack Amalek came undisguised, for since they came to oppose Torah observance within a Jewish setting (the synagogue or study hall), their identity as Amalekites, cousins of the Jewish people (see Bereishis 36:12), lent their challenge a stamp of authority. But here, in our Parsha, their aim was to undermine the observance of Torah in a non-Jewish setting (the workplace), so they came disguised as Cana’anites. Their message was: “We won’t bother you about what you do in the synagogue. But if you wish to be successful in the business world, forget about avoiding gossip, unfair competition, collecting interest, etc. You must act like a Cana’anite!”
In truth, however, such a notion is nothing but the evil enticements of Amalek. Judaism is not merely to be practiced at home and in the synagogue; it is equally as important, if not more so, to be a proud and ethical Jew at work too. For in this way we make the entire world—and not just the synagogue—“a home for God below.”
(Based on Likutei Sichos vol. 1, p. 208ff.)