Brother Wayne Teasdale, author of The Mystic Heart: Discovering a Universal Spirituality in the World's Religions andA Monk in the World: Cultivating a Spiritual Life, coined the new word "interspirituality." Sort of a mash-up between "interfaith dialogue" and "spirituality," interspirituality refers to the possibility or practice of integrating spiritual exercises and practices from more than one faith tradition into one's own expression of spirituality.
Obviously this covers a wide terrain. What it doesn't cover are efforts behind members of one religion to convert, suppress, or attack the adherents of another. So Christians who are out to convert Muslim are not engaging in an interspiritual practice! But a Christian who genuinely is interested in Muslim spirituality, and would like to integrate one or more Muslim practices (say, for example, keeping the Ramadan fast) into his or her faith as a Christian, is engaging in interspirituality.
Interspirituality could be as simple as reading a book to learn about another faith tradition, or as significant as an ongoing exercise to fully embody the observance of two (or more) religions on an ongoing basis. To illustrate this, I'd like to use a metaphor here. Being interspiritual is like having a relationship with more than one country.
Let's say you are an American, but you have a relationship with Japan. You might love Japanese culture: your house is filled with bonsai, and you catch every new anime movie as soon as it hits the theaters. Or, you might travel to Japan as often as you can afford it, just to spend time shopping in Tokyo or visiting Shinto shrines in the countryside. Maybe you work for a multinational corporation and you visit Japan regularly on business. Or you might be an activist who works with your Japanese counterparts in Hiroshima and Nagasaki to campaign for nuclear disarmament.
Maybe you get a job with the foreign service to work in Japan as an official representative of the United States; or - this would be the ultimate - you seek citizenship in Japan, without relinquishing your American citizenship, resulting in "dual citizenship." At this point you fully belong to both countries (United States law specifies that a person does not automatically lose US Citizenship when becoming a citizen of another nation, unless they explicitly renounce their prior citizenship).
Now, let's take this metaphor and apply it to interspirituality. Following my Japan-USA metaph0r, I'm going to write about interspirituality between Christianity and Buddhism. But the same logic could apply to any interspiritual engagement, involving any 2 or more traditions. Here are at least five approaches to interspirituality. Maybe there are more?
1. "Tourist" Interspirituality. Here a person is anchored in one faith, and has only a mild interest in another. An example might be a practicing Episcopalian who likes to read books by the Dalai Lama or Thich Nhat Hanh or Pema Chödrön. Once in a while she might attend a service or a program at a nearby Buddhist center, but her spiritual center of gravity remains primarily Episcopalian.
2. "Expatriate" Interspirituality. This one is common in our society today. The expatriate is unhappy with his "home" faith, and reduces or cuts off involvement with it. He then goes exploring, but may never fully engage with another faith either. Expatriates like to say they are "spiritual but not religious" and understand spirituality in a global or multi-faith context.
3. "Immigrant" Interspirituality. The immigrant is like the tourist, only in reverse. Immigrants move from one location to another. So they might let go of Christian observance and join a Buddhist sangha. Their identity is Buddhist and that's how they present their religious/spiritual identity to others. But they still have a casual relationship with their "home" faith, even if it's just attending holiday services when visiting Mom and Dad.
4. "Ambassador" Interspirituality. Like a member of the Foreign Service, ambassadors very consciously retain one spiritual identity while just as consciously engaging with another. Often this is done on a professional or leadership capacity. Here you find the Catholic priest who makes an annual retreat at a Zen monastery, or a college professor who practices one faith while researching and teaching about another. Ambassadors often become involved in explicitly interfaith or interspiritual programs, like Monastic Interreligious Dialogue or the Parliament of World Religions.
5. "Dual Citizen" Interspirituality. Finally, it is possible that interspiritual practice and identity becomes so essential to a person's journey that she must simply fully embrace both traditions (in my example, a Christian takes refuge as a Buddhist). While this is challenging (it's hard enough being an active and supporting member of one faith community, let alone two) and can be tricky on a cognitive level (after all, each religion contains its own customs or dogmas that cannot easily be reconciled with the teachings of other faiths), to a person who genuinely discerns they are called to walk this path, anything else would be unthinkable. Here the Christian remains a Christian, and yet also becomes a Buddhist. It's not a blending of the two into some sort of new age mishmash; rather it is a respectful and committed practice of engaging fully with each faith in its own integrity.
Certainly there are other ways to engage with a faith tradition different from your own. Do you have any ideas as to what that would look like?