The Indian Constitution was not an originally composed document by Ambedkar and others, but compiled by them mostly according to the materials existing already in several foreign Constitutions (constitutional documents of several countries), especially the American Constitution and the British Constitution.

However, the Indian Constitution, in spite of based on other Constitutions, ended up with a number of serious flaws including,

(1) the Indian Constitution granting Govt. help to people in education and jobs on divisive and discriminating basis according to their castes (family labels reflecting ancient family occupations), instead of giving people help in education and jobs logically and fairly according to recipient's current poverty and financial need; and

(2) the Indian Constitution allowing officially people the use of multiple divisive and discriminatory community oriented ancient / archaic religious laws, instead of having for all a single progressive and unifying UCC (uniform civil code: one law for all to dispense equal justice to everyone, irrespective of religion, race, caste and gender).

Misunderstanding about secularism in India (an old related post):

It seems the Indian public and politicians don’t have a clear idea about secularism. Even though some of them might have talked about implementing a Uniform Civil Code or UCC (one law for everyone in the country), there seems to be quite a confusion regarding the word “secularism” and the nature of a secular country, especially in relation to India.

While the traditional meaning of secularism reflects the separation of church and state, there is much ambiguity in defining and understanding “church” and “state” when it comes to practicing and implementing secularism. Thus, even in India where there are several religion based legal systems officially in practice and the Govt. grants benefits in education and jobs on the basis of caste, the word “secular” for India is used proudly and officially by everyone including the Govt., public and politicians.

Perhaps there is a kind of misguided charm and fancy in using the word “secular” even though it might not be applicable. Consider for example the Indian constitutional Amendment 42 (April 1, 1977), passed during internal emergency by Indira Gandhi, which provides for curtailment of fundamental rights, imposes fundamental duties and changes to the basic structure of the constitution by making India a "Socialist Secular" Republic, in spite of several religion based legal systems officially in use in the country.

What seems to have been ironic at that time that neither the ruling party (Congress) nor the opposition parties, including previous Bhartiya Jan Sangh or BJS (forerunner to the present Bhartiya Janata Party or BJP), realized the inherent contradiction and folly in using “secular” for India in the presence of religious laws. Moreover, many high officials from the BJP (party succeeding the BJS) still talk and write about Jinnah as a great secularist, even though Jinnah sought the division of India and creation of a country for himself and his community (i.e. Pakistan for Muslims) on the basis of religion where the official legal system would also be based on religion.

Needless to say, the use of the word “secular” for India is erroneous, unnecessary and totally negated by a lack of a non-religious UCC in the country. Moreover, when there are problems in the country arising mostly due to multiple religious legal systems (or the lack of UCC), people and some politicians tend to blame India’s secularism instead of a lack of UCC without realizing that India is not really secular because of multiple religious laws in the country.

by: Subhash C. Sharma (Jan. 27, 2011) ----  
https://creative.sulekha.com/misunderstanding-about-secularism-in-india_595225_blog