Rishi Sunak will become the country's first Hindu Prime Minister. Groups said the move would be a "historic moment" that shows the highest office "can be open to those of all faiths and ethnic backgrounds".
Mr Sunak is a practising Hindu and takes his Commons oath on the Bhagavad Gita, a sacred Sanskrit text. He was born in 1980 in Southampton to parents of Punjabi descent. His grandparents were born in India and emigrated to the UK from East Africa in the 1960s.
Speaking before Mr Sunak was confirmed as the next PM on Monday afternoon, Sunder Katwala, director of British Future, said: "It will be an historic moment if Rishi Sunak does become our first British Indian and Hindu prime minister, showing that the highest office in Britain can be open to those of all faiths and ethnic backgrounds. This will be a source of pride to many British Asians - including many who do not share Rishi Sunak's Conservative politics.
"Most people in Britain rightly say the ethnicity and faith of the prime minister should not matter. They will judge Sunak on whether he can get a grip on the job at a very difficult time. But we should not underestimate this important social change."
He pointed out that when Mr Sunak was born, there had been no Asian or black MPs in the post-war era. Mr Sunak's move to become PM is also taking place during Diwali. The religious festival is celebrated across the world and symbolises the victory of light over darkness, and good over evil.
The Hindu Forum of Britain tweeted that Mr Sunak had written to the group sharing his best wishes with those celebrating Diwali, and said they are wishing him in return "every success on this auspicious day". The 1928 Institute, a University of Oxford-backed British Indian think tank, said it is "incredible" to see Mr Sunak "closing in" on the Tory premiership.
A spokesman said: "Many of our grandparents were British subjects and now to see someone of Indian heritage in the UK's highest office would be truly inspirational. Mr Sunak's rise shows how the British Indian community has come a long way, and we hope this will serve as an inspiration for the next generation; although some will still attack Rishi Sunak for his heritage.
"Breaking this glass ceiling is a major achievement but we need more diversity in our government. We will judge Rishi by his policies and hope that our shared values across the diaspora such as seva are part of his leadership."
Krishna Halai, 27, an operations manager in tech from London, said: "I can celebrate a Hindu PM given the history of colonisation by the British in India, we are breaking barriers in politics. But Rishi specifically and some of the Indian/Hindu POC (people of colour) in ministerial positions I don't feel represents me and the kind of politics our families stood for when they first came to this country."
She will be celebrating Diwali with her family by sharing a meal and FaceTiming her relatives, including her father, in India.
When asked whether the significance of Mr Sunak becoming Prime Minister will also resonate in India, she said: "Yes absolutely - the UK diaspora communicate with family in India, the WhatsApp groups will buzz with photos and messages about it. Whether it contributes to greater UK-India relations, I don't know, but people will see it as a big step forward."
She added that Mr Sunak becoming PM "won't fix the underlying structures that make it so hard for people like us to achieve these positions in the first place".
