In several places, our Sages view the Korban Pesach (Paschal sacrifice) as serving to break the ties of idolatry. We read in Shemos Rabbah (16): "We find that when the Jewish people were in Egypt, they worshiped idols, as it is written (Ezekiel 20:8), "They did not cast away the abominations of their eyes."

Hashem told Moshe, "As long as the Jewish people worship the gods of Egypt, they shall not be redeemed. Go, tell them to abandon their evil deeds and atone for their idolatry." It is written: "Draw and take for yourselves" (Shemos 12:21). This is interpreted by the Mechilta as: "Draw your hands from idolatry and take for yourselves lambs, and slaughter the Egyptian gods and perform the Pesach."

The Mechilta also mentions several times that when their redemption began, the Children of Israel were commanded to renounce their idolatry. To allow time for this to occur, the lambs were only slaughtered four days after they were taken. "Draw and take for yourselves" is likewise interpreted by the Mechilta as: "Draw away from idolatry and cling to mitzvos." Furthermore, the refusal of the Children of Israel to heed Moshe's tidings due to "impatience and harsh labor" is explained there in terms of "their difficulty in separating themselves from idolatry."

The Ramban suggests that the purpose in sacrificing the Paschal lamb was to convince the Children of Israel that astrology has nothing to do with their redemption from Egypt, since they went out under the sign of Aries, representing the maximum strength of the lamb, the Egyptians' god. But the Ramban prefers Chazal's view that this mitzvah served to sever them from idolatry and to degrade the Egyptian deity.

It was well known in Egypt that harming even the smallest part of the lambs or sheep was tantamount to abusing their god, leading to capital punishment. Now, in an instant, the tables were turned. The Jews plundered the choice flocks of their masters, which were worshiped as gods. A wretched people who were enslaved lifted their hands against the herd of animals that their masters embraced as gods. Each took a lamb and bound it to his bedpost, in full view of Egyptians (Mishnah, Keilim 19:2).  No Egyptians could stop the Israelites as they watched them slaughtering the lambs in broad daylight. So that all of Egypt would recognize the outline of a lamb, it was not boiled in water but roasted, including the head, legs, and internal organs.

With casual contempt, the Children of Israel consumed all its flesh, down to the bone, and what remained at dawn was burnt. The Egyptian masses, accustomed to revering the sheep, seethed with frustrated anger at this affront.

The Zohar on Devarim explains the roasting of the lambs in accordance with the command (Devarim 7:25), "And burn their idols in fire." Likewise, the preparation, according to which the lamb was to be consumed complete, with legs and internal organs, was to make clear to the Egyptians that their deities had been burnt. The idea of the Pesach as severing the Jewish people from idolatry is made explicit in Ezekiel (20:6-7):

"On that day I raised My hand to take them out of Egypt to the land I sought out for them, flowing with milk and honey, the most beautiful of all lands. Then I said to them, 'Every man, cast away the detestable idols of his eyes. Do not defile yourselves with the idols of Egypt. I am Hashem your G-d."

From this it is clear that the Children of Israel were steeped in idolatry, and were commanded to turn away from it before leaving Egypt. As our Sages relate, when they stood with their backs to the sea, the prosecuting angel complained, "Are they any less idolatrous than the Egyptians?" The slaughter of the Pesach is therefore tied to Hashem's promise (Shemos 12:12), "I shall punish the gods of Egypt."

These punishments were meant to teach the Jewish people that the Egyptian gods were worthless, and certainly no match against the strength and might of the Creator. The same purpose was served by the fearless destruction of idolatry by the Children of Israel themselves, which found expression in the slaughter of the Egyptians' flocks before the Egyptians' eyes.