He was a prolific speaker (in both Hindi and English) on various spiritual traditions including those of Buddha, Krishna, Guru Nanak, Jesus, Socrates, Zen masters, Gurdjieff, Sufism, Hassidism, Tantra and many others. He attempted to ensure that no "system of thought" would define him, since he believed that no philosophy can fully express the truth.

An experienced orator, he said that words could not convey his message, but that his basic reason for speaking was to give people a taste of meditation:

“ I am making you aware of silences without any effort on your part. My speaking is being used for the first time as a strategy to create silence in you.
This is not a teaching, a doctrine, a creed. That’s why I can say anything. I am the most free person who has ever existed as far as saying anything is concerned. I can contradict myself in the same evening a hundred times. Because it is not a speech, it has not to be consistent. It is a totally different thing, and it will take time for the world to recognise that a tremendously different experiment was going on.

Just a moment … when I became silent, you become silent. What remains is just a pure awaiting. You are not making any effort; neither am I making any effort. I enjoy talking; it is not an effort.

I love to see you silent. I love to see you laugh, I love to see you dance. But in all these activities, the fundamental remains meditation.

He was often called the "sex guru" after some speeches in the late 1960s on sexuality. These were later compiled under the title From Sex to Superconsciousness. According to him, "For Tantra everything is holy, nothing is unholy",and all repressive sexual morality was self-defeating, since one could not transcend sex without experiencing it thoroughly and consciously. In 1985, he told the Bombay Illustrated Weekly,

“ I have never been a celibate. If people believe so, that is their foolishness. I have always loved women – and perhaps more women than anybody else. You can see my beard: it has become grey so quickly because I have lived so intensely that I have compressed almost two hundred years into fifty.”

Osho said he loved to disturb people – only by disturbing them could he make them think.Accordingly, his discourses were peppered with offensive jokes and outrageous statements lampooning key figures of established religions such as Hinduism, Jainism or Christianity. Concerning the virgin birth, for example, he said that Jesus was clearly a bastard, since he was not Joseph's biological son. An attempt on his life was made by a Hindu fundamentalist in 1980. Osho, however, said that the only thing he was serious about in his discourses were the jokes – they were the main thing, and everything else was spiritual gossip.