Given the pressure Schneider is under, I'm expecting to find a tetchy, harassed man who swipes back my questions with well-rehearsed one-liners that get a good laugh, but give nothing away. Instead, I find that he is gentle, almost apologetic. He immediately asks if I mind him eating a sandwich while we talk, and if he appears at all anxious, it is merely that he seems even keener to put me at my ease than I am to put him at his.
Schneider is little more than 5ft6in and with his wide-eyed, honest expression he looks exactly like the best friend you wished you'd had at school. Which makes it easy to understand why he was such a hit on the Jewish alternative comedy circuit at the beginning of his career back in 1991. His obvious passion and commitment to Jewish culture - he studied Yiddish at university - combined with a sharp wit and obvious charm had mothers queuing up to introduce their daughters to him. Which is as close to groupiedom as it gets in Jewish circles.
The Eleventh Commandment is a return to Schneider's Jewish roots. The play is littered with good gags, but is also a serious attempt to be more honest about his Jewishness than Schneider ever managed in his stand- up routine. The commandment in question is "Thou shalt not marry a shiksa (non-Jew)" - something Schneider knows a great deal about, as for the past six years he has been in a relationship with his non-Jewish partner, Sandy, by whom he has an 18-month-old daughter, Miriam. Which begs the obvious question.
Schneider admits that he has drawn heavily on his own and others' experience, but he is horrified at the suggestion that the mother in the play who implores her son not to finish off what Hitler started is his own mother. "I want to make it absolutely clear that she is not my mother," he says, before adding: "That really would be frightening." But I'm left with the distinct impression that this is said more for his mother's benefit than for mine. Because there are distinct resemblances: both are Holocaust survivors, and Schneider's relationship with his mother has been strained for much of the time he has been involved with Sandy.
Before he met Sandy, Schneider had been out with other non-Jewish women. This was tolerated by his parents as long as there were no signs that the relationship was serious. "There's an old Yiddish proverb, `You dance with shiksas, but you marry a Jew'," says Schneider. "And that's what my parents believed. In many ways, it's what I believed, too, because I've always been very into Jewish culture. Before Sandy came along it never occurred to me that I would marry out. So when I moved my computer into her flat and it became clear to my parents that I was committed to her there were real difficulties."
Schneider may chuck the odd throw-away gag into the conversation but overall he comes across as pretty serious. This isn't your typical playwright/actor trying to hype his wares. Much of what he is revealing is deeply personal and, while it's not always comfortable, it is affecting.
Schneider's situation was complicated by the presence of Skye, Sandy's four-year-old son from a previous relationship, who became a potent symbol for Schneider's parents of his disloyalty to his culture and a living reminder that they would have no blood Jewish grandchildren. "I understood their disappointment because tradition and continuity are paramount in orthodox Judaism," says Schneider. "I knew how much they wanted to have a Schneider-Goldberg wedding announced in the Jewish Chronicle to show they had succeeded as good Jewish parents. But I couldn't accept that what I was doing compromised my Jewishness or the Jewishness of my children. Why should an accident of matrilineage define one's religion and culture? Who is the more Jewish - the person who is a Jew by birth but otherwise has nothing to do with the culture, or the person who is technically a heathen but is immersed in Jewish traditions and regularly goes to synagogue?"
This conflict surfaced repeatedly in the early years of the relationship, and in retrospect Schneider feels that it might have been better to let matters evolve as faits accomplis rather than to confront them head on. "I'd rather forgotten to rebel as a teenager, and this issue was as good a pretext as any for letting rip with all my stored-up annoyances," he says. As a result, much of the communication during this time was "aggressive and unhappy" and there were long periods when neither party would speak to one another.
Paradoxically, Schneider and Sandy's decision not to get married further alienated his parents. Being involved with a shiksa was bad enough, but being involved and not getting married was even worse, and it was only Miriam's birth that brought about any real rapprochement.
Yet all the fall-out still remains. Sandy's parents find it difficult to forgive Schneider's for the way they have behaved towards their daughter, and Miriam is unlikely ever to see all four of her grandparents at the same time. And marriage between Sandy and Schneider has become increasingly less likely. "Occasionally we think it would be a good idea, but as soon as we get to the practicalities of where we would have it and who would sit where, it just becomes too much and we forget about it again," he says with a laugh but, as with so many of his jokes, his eyes betray the real sadness of the situation.
But if Schneider's involvement with Sandy has played hell with his relationship with his parents, it has done wonders for his relationship with his faith. Sandy's atheism ensured that there were no competing traditions, and her respect for his beliefs allowed him to reassess just what parts of Judaism were important to him. Ever since he first moved in, Schneider has made a point of having a Friday night Shabbos meal, where candles are lit and blessings are made over wine and bread, in which Sandy and Skye are invited to participate. "There's nothing compulsory about it and if Skye wants to watch TV that's fine," explains Schneider. "I'm not trying to turn him into a Jew; I just want him to be aware of where I come from and for him to make his own choice."
Certain areas have proved trickier than others. At one point in the Passover a passage is read in which Elijah delivers a tirade against non-Jews; throughout the years that Schneider read this in the traditional Hebrew, he didn't give it too much thought. But once he translated it into English so that the non-Jewish members of his family could be included in the ceremony, he realised he couldn't go along with it any more. "I could contextualise it by saying these people were living in real fear of pogroms at the time it was written, but that doesn't make it right now. So I omit that part from our Passover meal."
Such rethinking has not just alienated him from his parents - they now celebrate Passover separately - Schneider has also left the orthodox United synagogue for the haven of the Progressive synagogue. "I was worried it might be too Cliff Richard, but it's turned out just fine," he says. "I didn't want my children to inherit a religion which was so threatened by newcomers that it was always looking over its shoulder at anti-Semites. I wanted a glowing, welcoming religion that doesn't compromise itself. And I've found it."
At this point, Schneider, self-effacing to the last, suddenly becomes self-conscious. "Look, I don't want you to think I'm setting myself up as some kind of icon," he says. "I'm still groping towards many of the answers myself, and I have to be careful that I'm not just trying to prove my Jewishness to show my parents they were wrong. Besides, I'm still quite traditional at heart." How traditional? "Well, I sometimes find myself hoping that Miriam doesn't marry out." And what do you do about it? "I have a long, cold shower"n
`The Eleventh Commandment' opens at the Hampstead Theatre tomorrow.