ויירא יעקב מאד ויצר לו ... (ל-ח)
The Torah tells us that when Yaakov Avinu heard that his brother Esav was coming to greet him with an army of 400 ferocious fighters, he was very afraid. This seems to contradict the tremendous emunah that Yaakov, the great and pure tzaddik, had in Hakadosh Boruch Hu. Do we not read clearly that Hashem Himself promised Yaakov that He will be with him and protect him wherever he will go (כח-טו)? So what did Yaakov Avinu have to be afraid of?
R’ Simcha Sheps zt”l makes an interesting observation. For his own personal safety, Yaakov was not worried. He knew that Hashem would not allow any harm to come to him. But he looked off to the distance and “saw his brother Esav coming.” In other words, Yaakov looked into the future and saw how Esav would act towards his descendants. He would act as if he was a “brother” to them - and this is the most dangerous behavior of a goy to a Jew!
Rav Shimon bar Yochai tells us: "הלכה בידוע שעשו שונא ליעקב" - It is a known fact that Esav hates Yaakov, and when Esav puts on a facade and doesn’t outwardly show the hatred that is in his heart - it always blows up in the face of the Jew!
For this reason, Yaakov immediately cried out: "הצילני נא מיד אחי מיד עשו" - Save me from my brother, from Esav. Since he acts like a brother, I need extra protection from him for all the future generations of Yidden who might fall for the trap of the nations of the world. They will pretend to be friendly and act with brotherly love, showing great interest in the participation of the Jews in business, social circles and family life; only later to stab their Jewish brothers in the back.
Millions of Americans are assimilated with absolutely no connection to their rich Jewish heritage because of the play-acting and “brotherly-love” of Esav. A Jew must live with the middah of "לבדו" - he must stand apart from the nations of the world and not fall for their phony displays of brotherhood. Yaakov saw this millenium ago - and is warning us still!