The chief minister also praised Speaker Ram Niwas Goel for hosting the festival first-time at the Assembly premises.
"Festivals like Christmas are celebrated by all. This religious harmony is the soul of our country without which it will not survive," Kejriwal said.
Terming India as a bouquet of members of all castes, religions and tribes, he said "some people were working against this diversity".
"Some people want to spoil this bouquet which is not right," he said.
Supreme Court judge Justice Kurian Joseph congratulated the Delhi government and Assembly for the event.
The chief minister said that the "beauty of Indian secularism was that it welcomed all religions".
Attending the event, Christian priests also lauded the Delhi Assembly for hosting the Christmas celebration.
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