Complex sentence: The third day of Diwali is believed to be the most auspicious day as Lakshmi Puja is performed on this day and, with pomp and ceremony, she is invited into the homes of devotees to partake of the gifts that are a part of the puja.
Split into simpler sentences: The third day of Diwali is believed to be the most auspicious day as this is when Lakshmi Puja is performed. With pomp and ceremony, she is invited into the homes of devotees to partake of the gifts that are a part of the puja.