In the multicultural world in which I live, as a religious minority here in North America, it always brings a smile to my face when my identity as a Jew is positively acknowledged by someone who is not Jewish but has made the effort to learn (e.g.) the appropriate greeting. I believe that there is beauty in all religions and, though I am only well-versed in one, I know that I could find rituals that could be meaningful for me from another religious tradition. I also believe that others, not identifying as Jewish, could feel the same about the rituals that I grew up with. Does the same fuzzy feeling obtain if someone lives in accordance with some Jewish ritual or other, without any interest in being Jewish (per se)? Is there a limit to how much ‘sharing’ can respectfully occur among adherents of various religious traditions?
I do not think that there is, because I think that religion is a tool that humans have used for millennia to make meaning in their lives. As such, given that we now live in a world in which religious traditions can interact and mingle without a widespread outcry, I see nothing wrong with adding other avenues of meaning-making to one’s life. What higher compliment can you pay to another religious tradition than making the effort to go outside one’s cultural milieu and learn another tradition well enough to incorporate some aspect of it into your life? The key, though, is respect.
Be in contact both with peers of that religious tradition and with its leaders. Be aware that, no matter how genuinely you believe that you are expressing your love for other traditions, there will be religious adherents, both from your own community and the tradition whose rituals you are adopting, that view this amalgam very negatively. Finally, recognize that, just as no religion is monolithic, so too no ritual is monolithic. Learn of the varieties and the historical developments associated with a given ritual, and ensure proper adherence in private before public expression. Above all, be prepared to explain to anyone asking with genuine curiosity what it is that you are doing.
It is also important to consider whether a similar ritual is to be found in your own tradition. If not, it might be fruitful to consider why not, and then to share with your own religious community why you find this new ritual meaningful. If so, consider why the ‘foreign’ ritual attracted you more than the one you were more familiar with.
One potential criticism of such sharing is that it would make one a less proper adherent of religion x. However, if religion is about finding meaning in our lives, I see no need to segregate ourselves to the point where we can only live religiously with fellow adherents, and only ever express ourselves religiously through our own rituals. There is no competition between the religions, to see who can gather more adherents; the competition should be to see how humanity as a whole can attract the most people to seek lives of intentional meaning-making, in the particular ways that speak to them the most. Judaism does not ‘lose’ anything if some Jews use other religious language to express themselves, though over the long-term much can be gained by trying to create or fine-tune an existing Jewish ritual so that Judaism can capture what was meaningful about a ritual from another tradition.
I recognize that this is not a popular desire, and the road to true religious sharing will be paved by many more instances of people first taking the tentative step of learning of other traditions just enough to (e.g.) wish their Muslim friends and colleagues a Ramadan Mubarak, whereas adopting Ramadan as a personal practice will remain a fringe practice for the foreseeable future. It is important, though, to voice just how welcoming we ought to be to people seeking meaning who have come to the doorways of our religious traditions, as that can only lead to further integration and friendship.