Religion of course can be very divisive. As Richard Dawkins says it can inspire people to murder others because they have a barely distinguishable belief system. I don't agree with Dawkins that religion itself is a primary cause of violence, it is simply one more label by which we define tribal in-groups and out-groups - any ideology or physical difference will do just as well. In religion, emphasising commonality can bring people together, while emphasising difference has a danger of increasing hostility. On the other hand, by lumping everything together and glibly saying that it is all the same, we can muddy the water and distort the meaning of religions. And even if we can help bring religions together we do so at the risk of defining an in-group of religious people and an out-group of non-religions people.
I recently went on an interfaith peace march. In the current climate it seemed like a worthwhile cause, even if Oxford isn't exactly a religions warzone. It's hardly the Gaza Strip. I must admit that I felt a bit awkward - I've never done anything like that before, because I've never thought of myself as a religious person. But hey, Zen is technically a religion and I thought it was worth showing my face. It was good that all these different faiths were able to march in unity for the same cause and the speeches that were given, of course encouraged unity by emphasising common ground. But, I wondered at the way in which it seemed to exclude anyone who didn't have religious beliefs.
"Ladies and Gentlemen. We all believe in the same God..."
(Damn it the Hindus!)
"...We all believe in a Creator God..."
(darn! - Buddhists !)
"...We all have Religious Belief..."
(What are those Zen bastards doing here?!)
"...Well, at least we're not atheists!"
To say that 'all religions are essentially the same' is all very well, but what about polytheistic religions? What about the fact that Buddhists don't have a belief in God or in any transcendent absolute? What about religions which emphasise the ego such as Laveyan Satanism? What about non-religious 'peak experiences'. What about secular philosophies? What about ordinary life? We are always creating a perimeter somewhere. Attempting to find the unity of religion, Universalists expand the terriritory of 'the sacred' - the 'in-group' - but always leave an 'out-group'. Instead of finding unity, they are merely moving the borders of duality. Instead of dividing the world into Islam, Christianity, Buddhism etc, it divides the world into believers and non-believers, divine and profane, good and evil. How can we transcend all in-groups and out-groups and find a sense of the truly universal?
And in finding this common religious ground, there is also a strong temptation to bend the meaning of other faiths so that they fit into our conceptual (and dualistic) framework. Now I have a lot of respect for Baha'i - if I was to be a theist of any sort I'd probably be a Baha'i. Similarly, I hope my perception of Pure Land Buddhism isn't offensive to anyone. And I don't want to generalise from a single case, but I came across Baha'i online recently who was interested in learning more about Buddhism. It was no surprise that the branch they were most interested in was Pure Land. Pure Land is a populist, non-monastic strand of Buddhism aimed at ordinary lay practitioners. It is very dualistic in it's teachings, and is remarkably similar to the Abrahamic religions in form - salvation is gained not through personal practice but in faith in higher powers. Nirvana is characterised as the 'Pure Land' - almost exactly the same as the celestial realms of Hinduism and the Abrahamic faiths - a great example of convergent memetic evolution methinks - Richard Dawkins and Susan Blackmore would be delighted.
Why Buddhism doesn't quite fit
The majority of religions teach some sort of substantialism, which is inevitably dualistic - the world is divided into mind/matter, man/God, Atman/Brahma, sacred/profane, good/evil and so forth. They posit a transcendent power which is utterly distinct from ourselves and with which possibly in moments of mystical union we somehow become merged or receive communion with. Belief in the existence of a 'cosmic other' is something that has to be maintained by faith. Mystical 'union with the absolute' (if the faith allows such a thing) is a metaphysical event - the union of the substances of the human soul and of 'God'. They posit an eternal soul substance which corresponds to our sense of continuing personal identity. They reject the message of materialism, that our identity is produced by temporary physical form which is extinguished on death. Buddhism rejects both of these views as being based on the mistake of taking a conventional truth (identity) for an ultimate one (an immortal soul or a real self somehow arising from a temporary brain state).
Buddhism differs from other religions - apart from Taoism I think - in that there is no transcendent power - the mundane and the divine are not two, mind and matter are not two. Nirvana is not a separate realm from samsara; Buddha Nature is not separate from ordinary life. Buddhism teaches sunyata, or emptiness rather than divine substantialism. Buddhism teaches, not only the unity of 'the Divine', but the unity of the Profane with the Divine; not only the unity of religion, but the unity of religion with non-religion; not only the unity of man, but the unity of man, animals and inanimate objects; even the unity of unity and non-unity. Unity itself is not separate from non-unity - form (the relative, mundane) is not different from emptiness (the ultimate or universal nature of reality).
The union of man with the transcendent or divine is not a metaphysical event in Buddhism, nor is it even the collapse of a real duality. It is just the realisation that there never was a separation between the ordinary and the universal in the first place. It is the dropping of mentally created distinctions which had been taken as real dualities. The very duality between relative (man) and ultimate (God) is a constructed convention of the human mind.
But even to create a duality between dualism and non-dualism is more dualism. Experiences of the emptiness or unity of all things, which is seen in contrast to the ordinary dualistic world are regarded in Buddhism as incomplete because a non-dualism which exists in contrast to dualism is itself a dualistic viewpoint. Genuine non-dualism includes dualism, non-dualism, sacred, profane, God and non-God - nothing is excluded. Nirvana is the opposite samsara only from the perspective of those in samsara. Nothing is excluded. The point is that distinctions are real but only conventionally real, ultimately nothing is separate. To create a distinction between the conventional and the ultimate is again, conventional truth, ultimately there is no distinction. Nothing can be stated which is not conventional truth. This is why many Buddhist teachings appear dualistic in a way similar to other religions.
The barrier between self and cosmos in Buddhism is not a real physical or metaphysical separation or wall, it is a mental fabrication maintained by ourselves. At the moment of satori we fully realise its fabricated nature, we realise that there is no barrier to cross, nothing to attain.