Over the past several years, we have seen quite a number of Jewish or pseudo-Jewish practices picked up by non-Jews. While this isn't exactly a novel occurrence - Christians sort of invented it with the creation of their new religion not quite two millenia ago, and Christian "Passover seders" of various sorts have been going on for some number of decades- it's worth considering how Jews should react to the "democratization" of Jewish practices.
Whether it's the pseudo-Jewish kabbalah center (whose practices misrepresent kabbalah quite a huge amount) and its superstitious practices, or Justin Bieber saying the Shema before concerts, we can expect to see more of this kind of thing.
To a certain extent, a certain amount of syncretism is inevitable. We live in a culture that views religion through a Christian outlook - quite different than Judaism's: Judaism views religion as a system of practices, and primarily through a lens of communal practice for communal relationship,and salvation, insofar as Jews think about it, is a communal salvation. Christianity, on the other hand, views religion as primarily a belief-focused system (which is not to say that it doesn't have behavioral expectation, merely that behavior is the result of belief; in Judaism belief is necessary, but what one must believe is fairly limited: one must believe in one, undivided, disembodied God, who has never been and never will be embodied, also one must believe in some kind of reward and punishment system after death, details unspecified. That's it. All the rest is what you do: go and learn) and salvation is individual. There's a lot we could talk about here, in terms of how Jewish behavior and practices have been affected by the culture, but let's save that for another time, shall we?
The main point is that in a fairly philo-semitic culture, one in which religious affiliation has become extremely transient, and the average person changes affiliation at least once or twice over a lifetime, AND which is full of seekers, AND which views religious discipline as fairly boring, and spiritual fulfillment as something which is not entirely dissimilar from any other kind of consumable, it would be very surprising indeed if we did not see people experimenting with bits and pieces of various religious practices and attempting to grant them on piecemeal to create their own personal spiritual practice.
I already know - before I get a rash of comments saying so- that whatever I say about it here will have no effect on what people do. Jews aren't the only ones who have to suffer through this - Native Americans, and (subcontinental) Indians do as well (want to buy a dreamcatcher, or maybe some nice bindi?)not to mention a whole host of other religions of various stripes.
To begin with, maybe it's worthwhile to look at this from the other end, Jewish syncretism.
Jewish tradition tells us, (Pirke Avot,Chapter 4, Mishna 1)
"Ben Zoma said: Who is wise? He who learns from all people, as it is said: 'From all those who taught me I gained understanding' (Psalms 119:99). Who is strong? He who conquers his evil inclination, as it is said: 'Better is one slow to anger than a strong man, and one who rules over his spirit than a conqueror of a city' (Proverbs 16:32). Who is rich? He who is satisfied with his lot, as it is said: 'When you eat the toil of your hands you are fortunate and it is good for you' (Psalms 128:2). 'You are fortunate' -- in this world; 'and it is good for you' -- in the World to Come. Who is honored? He who honors others, as it is said: 'For those who honor Me will I honor, and those who scorn Me will be degraded' (I Samuel 2:30)."
In terms of"borrowing" from other traditions, I take this mishna as telling us a couple of things: First that it is fine to be aware of what other people do in the search for God and spirituality, and when it isn't inimical to Jewish tradition, that it's fine to use techniques that others have developed before us. Even within the Jewish tradition there are many ways to approach God, and some of them have been developed from seeing cultures around us use their own methods, and then using that kernel to develop a technique that works for Judaism.
In using techniques from other traditions as part of Judaism, the techniques need to be adapted - something that only happens over a long time- before they work, in the context of Judaism. More importantly, notice what I haven't talked about: importing wholesale rituals. Using techniques - meditation, song, additional restrictions on diet, etc- from other traditions, can over time, be brought into a generous spiritual practice fruitfully. But bringing in a specific ritual is unlikely to be a good idea: spiritual practices develop as part of whole disciplines, and one can't just take out a piece and expect it to help connect you to the universe.
Which is why learning from others isn't the only thing the Mishna talks about: it also warns us that we need to respect what we already have - until one actually has some decent knowledge of one's own traditions, running after others isn't going to be spiritually enriching, at least not in the long term. For one thing, taking bits and pieces out of context from other traditions denudes them of their power. Rituals - in all traditions, as well as Judaism- grow up in a holistic context. They are part of a system, and without the system, the pieces are merely magic, or even worse, products. Any spiritual practice requires discipline - doing things over and over, including things that might be difficult, or boring, until the parts come together to make you whole.
American culture has the unfortunate tendency to view everything as a product. If you spend your money, you should get something for it - and everything is for sale.
Buy a dreamcatcher, presto, you're a Native American Shaman (never mind that there are hundreds of nations each with their own traditions), buy some incense and beads, voila, you're a Hindu guru. But The hundreds of Native American traditions, Hindu spiritual practices, Voudoun, or whatever other religion- aren't products, and it's not enough to think that they're cool to get results from them.
Many Jews have decided that their own tradition is boring and needs to be tarted up with a little magic paint, but what they're missing is two things: first, that they probably don't actually know that much about their own tradition, and their decision that it's boring is a little premature.
When I was in college, I spent a lot of time thinking that Judaism needed to be rewritten here and there. I had the good luck that my temperament led me to do a lot of reading while I was busy working on this project. As I came to learn more about the extraordinary variety, various threads of tradition and how they work together, the tensions and richness of the incredible numbers of texts and commentaries that there are in Judaism, I came to see more and more that there was so much already there, that borrowing and changing from the outside wasn't really a project that needed to happen -sure, no tradition is perfect, but the seeds of renewal are already inside Judaism.
Second, that simply dropping your own traditions to go haring off after someone else's doesn't solve your problem: that you bring you with you. Spirituality isn't magic, and anyone who tells you that you can just run your finger over a string of letters and you'll be protected from harm is a charlatan, who may understand the desire that people have for easy answer and not putting much effort into something, but does not understand God.
Finally, the last part of the mishna offers, "Who is honored? He who honors others." The final thing is that we should honor the traditions of others. But using them without understanding their place in the system they come from is not honor. To the contrary, it's essentially telling the followers of that practice that their spiritual system is just a grocery store for you- you can go in, pick out what you like, and buy it and leave.
"Honor" is to respect that different religions have spiritual meaning, and to learn from them and honor them means to let those who are deeply embedded in them tell us their experience, explain their systems and meanings, and when invited, to participate as a guest. Each tradition may have things to tell us about the way the world works, or should work.
When I think of what wisdom Judaism can bring to people who are not Jews, I think of teaching, for example, Jewish textual traditions on how workers and employers are obligated to one another: In Jewish terms, mitzvot, obligations to other people, delineated carefully and thoroughly are spiritual practices just as much as lighting candles on Friday night, or praying in a minyan (group of ten Jewish adults). There are many kinds of things that Judaism can offer as learning to others without having them say the Shema. Respect and honor -for those who are interested in Judaism, but are not interested in being Jews- would be to learn about Judaism - perhaps attend a seder, but attending a seder is different than a non-Jew having a seder and attaching their own meaning to the event. Seders and the Shema are Jewish practices, not Jewish techniques.
Now, I don't think that Justin Bieber is a bad kid - in fact, I think it's sweet that he respects his manager enough to pay attention to the fact that he has a different religion, and to try to take some of it on. In my opinion, what he's doing is slightly different than some of the other reported celebrity syncretism that we hear about: Bieber does not appear to be seeking anything - he just wants to find some religious common ground. Nevertheless, while his motivation is purely sweet, I'm not sure that the way he's found to carry it out is a respectful one (unintentionally, I'm sure). For millenia, Jews have said the Shema not only as part of our daily prayer, but also in bad times, while being tortured or killed by people who were trying to force us to accept other religions. For a non-Jew to take on saying this prayer that declares the unity of God (by a practitioner of a religion that holds that God is not a unity, but a trinity) is problematic, and I can't say that I'm comfortable with it.
If non-Jews want to learn from Judaism, the same thing applies to non-Jews as to Jews looking to enrich their own experience - first of all, learn your own tradition better - you may find that it has what you are looking for within it already. Judaism tells us that the righteous of all nations have place in the World to Come, QED.
Secondly, if you still want to honor Judaism, or use it in some way in your own practice, borrow the techniques, not the rituals: learn about the Jewish idea of obligation as spirituality, think about how Judaism uses mitzvot, obligations, to make every (allowable) mundane thing you can do holy - there's a blessing for not just eating, but for elimination of waste (do I have to elaborate here?) -think about that! (Almost) anything can be made holy. The idea of separation- I could go on, but I'm sure you get the idea. (Justin, if you want something to do to include your manager during your prayers, or something you could do together, perhaps you could make a short prayer that isn't the shema, but which declares that you wish for all people to respect one another in their love for God).
Ultimately, while, I'm sure that people will go on borrowing practices whether I think it's a good idea or not, I would encourage people to think harder about what they are doing. Spirituality isn't there to make you feel good. In fact, sometimes it's there to make you feel bad. Doing someone's religious practice because it looks cool, is probably not a good way to develop spiritually. Religion is not a consumable, and you can't buy it. It is work, and you have to be committed to it.