There might be Buddhists who emphasize the pluralistic nature of existence more than others. There might be schools which call toward heavenly beings for salvation. Others might reject scriptural authority entirely in favor of a direct, personal realization.
The Buddha did not prescribe a particular dogma. He left his followers without a specific plan for organization. Fortunately, he did not leave them without inspiration or ideas.
People have believed in the Buddha’s words from the time he was born until now. However, nobody is an automaton. Nobody can fully express what they have heard. The light of enlightenment, universal as its followers might understand, will take on a new life within the mind of the one who experiences it. Anybody who has played the game of Telephone will understand. A message can be understood. Its transmission, in the exact same form through innumerable speakers, cannot be guaranteed. The message will inevitably change.
A spiritual seeker who lived 2,500 years ago likely would not be able to capably communicate to anyone now. Even if the language barrier could be broken, the cultural and psychological noise would prevent clear communication.
Many people spoke in the Buddha’s time and found followers. Not every speaker is worth hearing. The Buddha, however, had a particular skill in delivering a message crafted to the hearer. He used Brahmanical terms to educate those who upheld Vedic ideals. He also competed with other unorthodox movements who had their own takes on the way to escape suffering. There are thousands of pages solely devoted to the Buddha’s words.
The history of Buddhist communities was never linear, nor was it guided by a conscious effort to unify all Buddhists under a single “church” in the style of the Catholic Church in the West. Various schools organized organically and voluntarily around particular texts, around local Sanghas, and around certain teachers. This unplanned and diffuse proliferation led to a bewildering variety of schools with their own emphases, but all remained united in their belief in the Four Noble Truths, the Noble Eightfold Path, and the Non-Self.
The Original Wisdom schools (of which only the Theravada survives today) retained the language and culture of the Brahmanical society from which they grew. During the time of the Original Wisdom’s flourishing, sutras emerged which claimed to be spoken from the mouth of the Buddha and heard by his followers.
From these sutras, their commentaries, and other philosophical treatises emerged alternative ways of belief. These new ways stretched the original Sangha’s teachings and rituals into new frontiers. Early schools of thought included Yogachara and Madhyamaka, advocating pure idealism and robust skepticism, respectively. Most Mahayana descendants have strains of these two schools in their philosophical corpus. Yogachara offers an analysis of the psychological components of the Buddha’s teachings. Madhyamaka takes the no-self teaching of the Buddha a few steps further to suggest a no-enduring-thing policy.
The Tendai school is a prime example of a school based upon the supreme authority of a particular sutra (the Lotus Sutra). The Kegon school is another (the Flower Garland Sutra). The Pure Land school similarly favors its treasured sutras as the culmination of the Dharma. Each of these three schools has deep roots in China, where certain sutras captured the imagination and affection of adherents and a bounty of profound teachings spread throughout China and beyond.
The Vajrayana school possesses a vast reservoir of well-preserved and intricate texts and rituals. At the core of the Vajrayana is the admirably refined usage of rituals–mantras, tantras, and ornate visual representations of the divine realms.
One quick note: Throughout this website, the classifications of the estimable Junjiro Takakusu is used.