Based On the legend, Diwali is celebrated to mark the return of lord Rama, his wife Sita, and brother Laxman to Ayodhya following the completion of 14 yrs of exile in the forest, and after the defeat of Lanka king Ravana who had abducted Sita. Hinduism is often called Sanatana https://www.youtube.com/shorts/kZdI4efhhkA