Parsha Mitzvot: Bo: Mitzvah 17 – Concept 412
“No alienated man may eat from it.” (Exodus 12:43) An apostate is prohibited from eating the Pesach offering. (Rambam, Hilchot Korban Pesach)
The apostate is permitted to eat the Matzah and Marror because he shared the suffering of slavery, and the thrill of exile with us. However, the Pesach offering is not only a celebration of the past, but of the ultimate redemption, which the apostate denies, as well. We welcome an apostate to pray with us, to learn with us and to observe commandments with us. However, we do not allow him to partake of a Mitzvah, which is a statement of our belief in a future that he denies. We would lose our connection with the Korban by allowing it to be eaten by one who denies its essence.
It is obvious that an apostate would not care whether he is permitted to eat of the Pesach offering or not. This is actually an instruction for those who believe, to not allow an apostate to join as part of their group that is participating in this Offering.