What is the accepted truth of Buddhism??

In Shiva Purana there is a story where an ascetic asks Lord Vishnu "Lord why did you bring Buddha into this world and created a confusion ?" Lord Vishnu replies "I created Buddha because the Dharma has been inflitrated by outsiders so I have created my own enemy from myself. He will criticise the Vedas, ridicule the rituals of Brahmin, deny the Upanishads and hence would cleanse the Dharma." Then there is a dialogue between Buddha and Vishnu where Buddha asks Lord Vishnu to issue the duties that he has to perform. What are the other truths about it?