Interspirituality

"It seems to me that the world's religions are like siblings separated at birth. We've grown up in different neighborhoods, different households, with different songs and stories, traditions and customs. But now we've been reunited, and, having found each other after so many years apart, we look into each other's faces and can see the family resemblance. We're back together again, and it's very good."
--Richard Watts

Before his death in late 2004 from cancer, Brother Wayne Teasdale advocated what he called intermysticism and interspirituality, most notable in the books A Mystic Heart and A Monk In The World. He was fond of citing Thomas Keating and his initiative, the Snowmass Conference, a group made up of single representative from fifteen different religions.
In particular Teasdale promoted their "Guidelines for Interreligious Understanding":

The Snowmass Conference's Guidelines for Interreligious Understanding The world religions bear witness to the experience of the Ultimate Reality to which they give various names: Brahman, the Absolute, God, Allah, (the) Great Spirit, the Transcendent. The Ultimate Reality surpasses any name or concept that can be given to It. The Ultimate Reality is the source (ground of being) of all existence. Faith is opening, surrendering, and responding to the Ultimate Reality. This relationship precedes every belief system. The potential for human wholeness -- or in other frames of reference, liberation, self-transcendence, enlightenment, salvation, transforming union, moksha, nirvana, fana -- is present in every human person. The Ultimate Reality may be experienced not only through religious practices but also through nature, art, human relationships and service to others. The differences among belief systems should be presented as facts that distinguish them, not as points of superiority. In the light of the globalization of life and culture now in process, the personal and social ethical principles proposed by the world religions in the past need to be re-thought and re-expressed. from Speaking of Silence: Christian and Buddhists on the Contemplative Way by Thomas Keating

Do you think they are necessary guidelines? Are they sufficient?