Prince Siddhartha, who was later called Buddha, was a Hindu. He didn’t promote “Buddhism”. Emperor Ashoka, who was born a few centuries later, promoted Buddhism. He wanted his subjects to follow what Buddha had taught and what was compiled in some councils, long after Buddha’s death. The story goes that Ashoka felt so much repentance after a cruel war that he converted to Buddhism. This story may not be true. Another version says that, as he had killed his brother to get to the throne, he was censored by a Brahmin council. Consequently, he declared himself a Buddhist.
Whatever may be the reason for his conversion, fact is, that it needs force to push a new faith onto people, and Ashoka did use force, especially against Jains and Brahmins. It also needs the claim that the new faith is better than the old one, otherwise, why would people change their faith?
Christianity and Islam repeated this recipe of using force and unsubstantiated claims a few centuries later with grave consequences for humanity. Luckily Buddhism didn’t have such negative outcome because Buddha’s teaching was basically Hindu teaching, which doesn’t divide humanity into those who are saved and those who are damned, depending on what they believe. Moreover, most Buddhists reverted back to Hinduism after some centuries, and many were killed in the brutal Muslim invasion. Yet Buddhism survived in other countries in Asia.
Today we can observe that Buddhists usually insist that theirs is a different religion, whereas Hindus don’t see much difference and not only respect Buddha, but also consider him as one of their avatars. Buddhists follow
only Buddha, whereas Hindus have so many sages to choose from. To justify their claim that Buddhism is a separate religion, Buddhists try to find “differences” in regard to Hinduism. These differences are often only
differences in terminology and not real differences.
Long ago, in 1985, I had a chance to meet the Dalai Lama together with two German friends. When the Dalai Lama noticed that I had dived more into Hinduism than into Buddhism, he asked me a question: “Do you think that the concept of Atma in Hinduism makes a difference to Buddhism?” “Of course not”, I replied. “The Upanishads clearly state that Atma is Brahma(n). It means, there is no separate Self (Atma). All is the one, pure
Consciousness, called Brahman or Paramatma.”
A few weeks later I had a chance to meet Sakya Trizin, the head of the Sakya sect of Tibetan Buddhism, and asked him: “What is the difference between Hinduism and Buddhism?”
“The concept of Atma”, he immediately replied. I was not surprised because I had heard it from foreign Buddhist friends several times: in Buddhism there is no-self, yet Hinduism postulates a self (Atma). And their conclusion was: That’s why Buddhism is closer to the truth.
Yet what Buddhists call Clear Mind or Nirvana, the Vedas call Brahman, Paramatma or simply Tat (That). Terminology is different, Truth is the same.
So it means, there is a slight rivalry, and in some cases even a massive rivalry. For example, I once read very negative, even abusive, comments on Hinduism by a Sri Lankan Buddhist monk. He was then asked by one of his disciples, “But isn’t Hinduism the mother of Buddhism?” The monk’s reply: “Even a bad mother can have a good son”. I remember it because it shocked me.
The attempt to look superior exists also today on social media, for example on Twitter. There are some handles which not only stress the supremacy of Buddhism but also demonize Hinduism. For example, they claim
that Hindus brutally exterminated the Buddhists in India, when in fact it was done by the Muslim invaders.
So, there is rivalry, but only from the Buddhists’ side, because they need to justify why they are not one of the many branches of Hinduism, but a separate religion altogether. Hindus do not feel the need for demarcation to
other views. They are the least dogmatic of all. Hinduism would happily integrate Buddhism as one more branch of the vast Sanatana Dharma, if Buddhists allowed it…