Diwali or the Festival of Lights, marks the Vedic New Year, and is associated with many of the Supreme Lord’s pastimes on earth. Diwali is celebrated on the occasion of Lord Rama’s return to Ayodhya after completing the 14 year exile and defeating the great demon Ravana.  
For ISKCON members, this day is most notable because it marks the return of Lord Rama, an incarnation of Krishna, to his kingdom of Ayodhya, after his defeat of the evil king Ravana. Rama was welcomed by all the citizens who lit lamps or dipas illuminating the sky for his joyous return. It also marks a day during Lord Krishna’s advent when He dispatched the demoniac Narakasura.
Diwali thus signifies the victory of light over darkness and good over evil. The festival also symbolizes a time for spiritual renewal by lighting a lamp within our own hearts for spiritual enlightenment and by welcoming the Lord into our lives. The festival is often celebrated with elaborate firework displays, lighting Diwali lamps and feasting.