This is the ordinance of the Pesach; no stranger shall eat of it.. (Shmot 12:43)

[edu]

"This is the ordinance of the Pesach; no stranger shall eat of it... "(Shmot/Exodus 12:43)

According to the Talmud (Shabbat 87a) this was the justification used by Moshe{Moses} to break the tablets of the ten commandments as a response to the sin of the Golden Calf

‘He broke the Tablets’: how did he learn [this]? He argued: If the Passover sacrifice, which is but one of the six hundred and thirteen precepts, yet the Torah said, there shall no alien eat thereof:11 here is the whole Torah, and the Israelites are apostates, how much more so!12 And how do we know that the Holy One, blessed be He, gave His approval? Because it is said, which thou brakest,13 and Resh Lakish interpreted this: All strength to thee14 that thou brakest it.
Footnotes
(11) Ex. XII, 43. ‘Alien’ is interpreted, one whose actions have alienated him from God, v. Targum Onkelos a.l.
(12) They are surely unfit to receive the Torah!
(13) Ibid. XXXIV, 1.
(14) Lit., ‘thy strength be well’, an expression of approval. For further notes V. Yeb., Sonc. ed., pp. 412ff.

[kyel]

Does this mean that if you wanted to invite a gentile to a seder he would have to be circumcised? I'm sure there are a ton of reform and messianic "Jews" running around doing this...

[edu]

Even when we don't have the Pesach sacrifice (because the secular government of Israel prevents us from offering it today) we still have the following issue of inviting gentiles to a seder
http://www.yeshiva.co/ask/?id=659

30 Nisan 5763
Inviting non-Jews to the Seder

Rabbi Jonathan Blass

Question:
At our Seder, one of the non-observant guests asked if one could invite non-Jews to the Seder. How does one answer such a question without giving the impression that orthodoxy is intolerant?

Chag Kasher v’Sameach

Answer:
Without going into detail explain that inviting a gentile to on a festival involves overcoming technically many halachic difficulties (you can mention that the laws forbidding cooking apply on festivals as they do on Shabbat with only few exceptions) and this makes it almost impossible for the average family. Point out that when diplomatic protocol requires it, Israeli embassies have been able to have gentile guests and have overcome the obstacles halachically (see Mishna Berura 512 6).

When the Pesach sacrifice will be restored, we will have an additional problem inviting them to the seder, because they 1) Are forbidden to eat the sacrifice unlike the Jews who must eat from it 2) They have the status of Zavim (a type of ritual impurity) and by touching, moving or spitting on Jews who have purified themselves, they can ruin the purity of either the Jews participating in eating the Pesach sacrifice or they can invalidate the meat of the sacrifice entirely.

[Tag-MehirTzedek]

Even when we don't have the Pesach sacrifice (because the secular government of Israel prevents us from offering it today) we still have the following issue of inviting gentiles to a seder
http://www.yeshiva.co/ask/?id=659When the Pesach sacrifice will be restored, we will have an additional problem inviting them to the seder, because they 1) Are forbidden to eat the sacrifice unlike the Jews who must eat from it 2) They have the status of Zavim (a type of ritual impurity) and by touching, moving or spitting on Jews who have purified themselves, they can ruin the purity of either the Jews participating in eating the Pesach sacrifice or they can invalidate the meat of the sacrifice entirely.

 + We would be eating it in Jerusalem the Holy city and not in our homes so they wont be near the proximity.
 + Only those who are announced before the sacrifice is brought can partake of it. New people (even Jews) aren't able to join in it.
 + The issue of wine and drinking together.
 
 - About ritual impurity I thought that gentiles don't have it, only Jews can have it.

[edu]

Quote from Tag-MehirTzedek

+ We would be eating it in Jerusalem the Holy city and not in our homes so they wont be near the proximity.
 + Only those who are announced before the sacrifice is brought can partake of it. New people (even Jews) aren't able to join in it.
 + The issue of wine and drinking together.
 
 - About ritual impurity I thought that gentiles don't have it, only Jews can have it.

During the 2nd Temple, we had Gentiles in the city of Jerusalem, who came to bring their own sacrifices or for other reasons. The Midrash tells for example how the spit from a Gentile once made a Cohain Gadol ritually impure and so he had to be replaced by his brother on that day.
במדבר רבה (וילנא) פרשת במדבר פרשה ב
מעשה בשמעון בן קמחית שיצא לדבר עם המלך הערביים וניתזה צינורא של רוק מפיו על בגדיו וטימאוהו נכנס יהודה אחיו ושימש תחתיו בכהונה גדולה אותו היום ראתה אימן שני בניה כהנים גדולים אמרו חכמים שבעה בנים היו לקמחית וכולן שימשו בכהונה גדולה

 Regarding the impurity of Gentiles as Zavim, see Shabbat 83a, Nida 43a. It appears to be a rabbinic safeguard and not De'oraita.