Excerpts below taken from an article on www.jewishsexuality.com
Our Sages tell us that we were redeemed from Egypt due to the merit of the two mitzvot (commandments) which G-d commanded us to perform on the eve of our departure - the Paschal sacrifice and the brit milah. Both of these commandments were designed to free us from our spiritual slavery to the lusts of the body, and liberate us to true freedom as servants to G-d. Among a cornucopia of bestial doings, the Egyptians worshipped the lamb. Among the domestic beasts, sheep are known for their fecundity. In a similar manner, licentiousness was an integral part of this idol worship. Our Sages teach us that the Jewish People only worshipped idols as an excuse to engage in the sexual debauchery that went with it.
In commanding every Jewish household in Egypt to take a lamb, the Egyptians' god, and slaughter it for the Pesach offering, G-d was commanding us to slaughter the physical lusts in ourselves that lead to the perversion of the holy marital union, and to the pollution of the holy life force of our nation. Interestingly, we were commanded to tie the lambs to our bedposts, not to the door, or the window, or kitchen table, but to our beds, precisely to drive this point into our individual and national consciences that we are to be a holy people, separated by the purity of our sexual lives from all of the other nations in the world.
This is the very same lesson of the brit milah. Only a man who was circumcised was allowed to partake in eating the Passover lamb. The removal of the foreskin both symbolizes, and physically effects, the removal of the impure physical lusts.
The Pesach Lamb on the eve of our departure from the bondage of Egypt and from our servitude to its debauched and immoral culture, we were called to renew the Brit of our Forefathers, the founding Covenant between G-d and the Jewish People, whereby we safeguard the purity of our sexual lives, symbolized by the brit milah, and G-d, for His part, promises us the Land of Israel as our eternal inheritance. Thus the Zohar teaches that in the merit of the blood of the slaughtered Paschal lamb (the korban Pesach) and the blood of the brit milah, we were redeemed from the spiritual dungeon of Egypt.