Question:

Why has there arisen in every generation those who wanted to annihilate the Jewish population? Every year, I read this in the Hagadah, but now I am wondering why this animosity?

Answer:

There are many explanations given, but they seem to overlook an obvious fact of history: Conquerors generally work towards creating a homogenous society where all will follow the same authority and live a similar lifestyle.

The Catholic Church wiped out any vestige of paganism, shamanism, pantheism, etc. in Europe. As soon as any heresy arose, it was brutally crushed—often with no survivors. Islam acted similarly, at times marginally tolerating Christians and Jews, but reacting ruthlessly to whatever was considered a heresy to Islam. Before them, the Hellenist spirit of the Macedonian and Roman empires worked in like manner to create a homogenous culture that would be easier to dominate and control. The story of Purim tells us that Haman had a similar plan in mind.

Given these facts of history, the question is really the opposite: How could we possibly have survived, while every other "heresy" was destroyed? In fact, the Church consistently blamed every heresy upon the Jews—yet while they systematically wiped out every vestige of those heresies, they somehow let the Jews survive.

Historians will give their many explanations. A historian is someone who can give a natural explanation for anything. As for the Hagadah, it clearly tells us that the only explanation is a purely supernatural one:

Blessed is He who keeps His promise to Israel, blessed be He. For the Holy One, blessed be He, calculated the end of the bondage, in order to do as He had said to our father Abraham at the Covenant between the Portions, as it is said: "And He said to Abraham, `You shall know that your seed will be strangers in a land that is not theirs, and they will enslave them and make them suffer, for four hundred years. But I shall also judge the nation whom they shall serve, and after that they will come out with great wealth.'"

...and then we say:

This is what has stood by our fathers and us. For not just one alone has risen against us to destroy us, but in every generation they rise against us to destroy us; and the Holy One, blessed be He, saves us from their hand.

Let me know if this helps.

Rabbi Tzvi Freeman for Chabad.org