One of the popular scholars of comparative religion and philosophy, he was among the scholars of 20th century that built a bridge between Eastern and Western thought showing each to be comprehensible within the terms of the other. He introduced Western idealism into Indian philosophy and provided substantial exegesis of India's religious and philosophical literature to English speaking people. His academic appointments included the King George V Chair of Mental and Moral Science at the University of Calcutta (1921-?) and Spalding Professor of Eastern Religions and Ethics at Oxford University (1936-1952).
In 1921, he was appointed as a philosophy professor to occupy the King George V Chair of Mental and Moral Science at the University of Calcutta. Radhakrishnan represented the University of Calcutta at the Congress of the Universities of the British Empire in June 1926 and the International Congress of Philosophy at Harvard University in September 1926. In 1929, Radhakrishnan was invited to take the post vacated by Principal J. Estlin Carpenter in Manchester College, Oxford. This gave him the opportunity to lecture to the students of the University of Oxford on Comparative Religion. For his services to education, he was knighted by the British Government in 1931, but did not use the title in personal life. He was the Vice-Chancellor of Andhra University from 1931 to 1936. In 1936, Radhakrishnan was named Spalding Professor of Eastern Religions and Ethics at the University of Oxford, and was elected a Fellow of All Souls College. In 1939, Pt. Madan Mohan Malaviya invited him to become Vice-Chancellor of Banaras Hindu University. He continued as its Vice-Chancellor till January, 1948. When India became independent in 1947, Radhakrishnan represented India at UNESCO, and was later India's first ambassador in Moscow, USSR, from 1949 to 1952. He was also elected to the Constituent Assembly of India.
Radhakrishnan was elected as the first Vice President of India in 1952. In 1956, his wife Sivakamamma died. They were married for over 51 years. He was elected as the second President of India (1962-1967). When he became President, some of his students and friends requested him to allow them to celebrate his birthday, 5 September. He replied,
"Instead of celebrating my birthday, it would be my proud privilege if 5 September is observed as Teachers' Day."His birthday has since been celebrated as Teachers' Day in India.Radhakrishnan along with Ghanshyam Das Birla and few other Social Workers in pre independence era formed Krishnarpan Charity Trust.
He was elected as a Fellow of the British Academy in 1938. He was awarded the Bharat Ratna in 1954, and the Order of Merit in 1963. He received the Peace Prize of the German Book Trade in 1961, and the Templeton Prize in 1975, a few months before his death. He donated the entire Templeton Prize amount to Oxford University. The Oxford University instituted the Radhakrishnan Chevening Scholarships and the Radhakrishnan Memorial Award in his memory.
It is not God that is worshipped but the authority that claims to speak in His name. Sin becomes disobedience to authority not violation of integrity.
"Those who have read the author's previous volumes or have heard him speak are accustomed to associate with him warmth and vigor of style, penetrating flashes of keen analysis, and detailed familiarity with past and present philosophies in both east and west. In these respects none will find the book disappointing."
"I believe this is the first time I have written a review when no negative criticism of any kind seemed to me warranted. ... No one interested in Indian thought who does not expect to master the original materials can dispense with this book."