As for why Passover wouldn't be taught while Genesis should (according to Fundamentalists): Easy. Genesis is pretty much the existence of G-d. If you refute this then the rest doesn't matter.

But I am always amused by the rigid Christian reactions to our book (what they derisively refer to as the Old Testament).  We (Jews) are taught to learn it, question it, interpret it, interpret the interpretations of it, and to constantly debate its meaning and the significance of its lessons in our lives.  I have never seen a Jewish sermon or teaching that ends with an easy lesson on what it all means (or even a single answer of any kind).  The passover service (called the Seder, and only known among Christians because of a Da Vinci painting) typically includes references to historical debate on the significance of the holiday.

To me, the focus is on freedom.  We repeat several times throughout the Seder that once we were slaves and now we are free.  Perhaps our non-Jewish friends here can put aside the horror of blood, lice, frogs, and the slaying of the first born and join us in celebrating that (despite several serious setbacks for our people over the intervening three thousand years) we are free.  Next year, may all people be free.

"..An Israeli historian suggests the diaspora was the consequence, not of the expulsion of the Hebrews from Palestine, but of proselytising across north Africa, southern Europe and the Middle East...

Every Israeli knows that he or she is the direct and exclusive descendant of a Jewish people which has existed since it received the Torah (1) in Sinai. According to this myth, the Jews escaped from Egypt and settled in the Promised Land, where they built the glorious kingdom of David and Solomon, which subsequently split into the kingdoms of Judah and Israel. They experienced two exiles: after the destruction of the first temple, in the 6th century BC, and of the second temple, in 70 AD...

But during the 1980s an earthquake shook these founding myths. The discoveries made by the "new archaeology" discredited a great exodus in the 13th century BC. Moses could not have led the Hebrews out of Egypt into the Promised Land, for the good reason that the latter was Egyptian territory at the time. And there is no trace of either a slave revolt against the pharaonic empire or of a sudden conquest of Canaan by outsiders. Nor is there any trace or memory of the magnificent kingdom of David and Solomon. Recent discoveries point to the existence, at the time, of two small kingdoms: Israel, the more powerful, and Judah, the future Judea. The general population of Judah did not go into 6th century BC exile: only its political and intellectual elite were forced to settle in Babylon. This decisive encounter with Persian religion gave birth to Jewish monotheism.

Then there is the question of the exile of 70 AD. There has been no real research into this turning point in Jewish history, the cause of the diaspora. And for a simple reason: the Romans never exiled any nation from anywhere on the eastern seaboard of the Mediterranean. Apart from enslaved prisoners, the population of Judea continued to live on their lands, even after the destruction of the second temple. Some converted to Christianity in the 4th century, while the majority embraced Islam during the 7th century Arab conquest.