In the Lotus Sutra, the Buddha finally introduced the One Vehicle of Buddhahood, which unifies and ultimately transcends the previous three vehicles. The One Vehicle is the teaching that all beings can attain Buddhahood. Even those following the Two Vehicles of the voice-hearers and privately awakened ones, whom the Buddha declared unfit to attain Buddhahood, would be able to do so. In fact, the Lotus Sutra states that they had been on the One Vehicle all along, though they did not know it. This attainment of Buddhahood by those following the Two Vehicles is the main theme of the first half of the Lotus Sutra. In order to ensure that this teaching is understood, the Buddha taught it in many different ways. He used philosophical discourses, parables, similes, past-life experiences, and ultimately gave predictions of Buddhahood to all his many disciples.

More astonishing was the fact that the Buddha predicted that even his traitorous cousin, Devadatta, who had tried to kill him and take over the Sangha, would attain Buddhahood in the future. Shortly after this prediction, an eight-year-old dragon-girl transformed into a Buddha before the eyes of the whole assembly – despite the culturally perceived impediments of her sex, her age, and her birth as an animal. These examples extend the idea that even those previously believed unfit to attain Buddhahood would be able to do so in the end.