ACCEPT, ADOPT AND ADAPT
The Buddha was even ready to accept other views if they were useful to explain the reality of the Four Noble Truths. According to Ven. Sangharakshita,
'Though the Buddha rejected in the most categorical manner a great many of the beliefs and practices current in his time, references to which will be found scattered all over the pages of the scriptures, it should not be concluded that his attitude towards contemporary trends of thought was entirely negative, much less still unsympathetic or hostile - words which have no meaning in relation to a Fully Enlightened and Wholly Compassionate One. He was as ready to accept as to reject; in fact he was more ready to reject than to accept. For he knew that a positive method of teaching was more appealing, more likely to find entrance into the hearts and minds of his audience, than a purely negative and destructive one, however correct and logical the latter might be. Consequently we find the Buddha constantly putting - if we may be permitted a metaphor which he probably would not have used, even if he had known it, of putting old wine in new bottles. He does not condemn the practice of ceremonial ablution, for instance, so much as insist that real purification comes by bathing, not in the Ganges as people thought, but in the cleansing waters of the Dharma. He does not ask the brahmin to give up tending the Sacred Fire, with which so many ancient traditions and so much religious emotion were bound up, but to remember that the true fire burns within, and that it feeds not on any material object but solely on the fuel of meditation. These examples of the Buddha's capacity to utilize Indian traditional practices for the purposes of his own Teaching could be paralleled by a hundred others from the same canonical sources. Though self-torture had been definitely rejected as a means to Enlightenment, he permitted thirteen ascetic practices, called dhutangas, out of hundreds of similar ones, to the members of his Order, not because he considered them necessary, but because there was a popular demand for them and because they were in any case not positively harmful.'
'This spirit of adaptation and assimilation was one of the factors which enabled Buddhism to spread so rapidly and easily, and with the minimum of opposition, among races and peoples whose traditions and cultural backgrounds were in many ways quite different from those of India.' (Sangharakshita, Survey of Buddhism, p 81)
As Ven. Sangharakshita puts it so eloquently, Buddhism adopted and adapted to any culture it encountered as it spread all over Asia in the first thousand years of its history. Buddhism never sought to replace other religions wherever it spread. Rather it accepted anything 'not positively harmful' (like killing), in other cultures and by assimilation made these practices its own. For example Buddhism did not condemn the belief in tree spirits which the pre Buddhist Thais and Sri Lankans had, but allowed them to continue because it ensured a respect and love for nature. As a result Buddhism fostered the development of unique forms of culture so that we have today Chinese Buddhism, Tibetan Buddhism, Japanese Buddhism which are culturally distinct but which all agree with the basic doctrinal teachings. In fact we can even see the beginnings of a new Malaysian brand of Buddhism which is quite distinct from the Buddhism practised in traditionally Buddhist countries like Sri Lanka, Myanmar and Thailand.