Many people press the argument that since Pakistan is a multi-lingual country and to a certain degree multi-ethnic and multi-cultural, that it will not survive as a single state unless Islam is enforced as a unifying factor.
This argument is absurd and seriously flawed.
There are alot of Muslim and non-Muslim countries that are multi-lingual and multi-ethnic and they have managed to survive without any religion as a unifying factor. In some cases most notably in Britain, religion is one of the key dividing factors between the Germanic English and the Celtic Irish aside from slight difference in ethnicity.
The same can be said for Pakistan, with rival Shia-Sunni conflicts tearing up the country's religious infrastructure.
The same can be said for India, in which religion has contributed to the country's inter-conflicts such as those between "hindus" and Sikhs or "hindus" and Muslims or "hindus" and Christians.
Iran, Afghanistan, Iraq, Turkey and the north African Arab states are all multi-lingual and Islam has definitely not contributed to their unity. Neither have their governments tried to use Islam as a common unifying factor. In the case of Iran, it has just led to more tensions between the Shia majority and Sunni minority.
The same again can be said in the case of Pakistan. With the Shia minorities resisting Sunni-state control.
Other arguments have also been laid in favor of embedding religion into the state rule such as:
-The Bangladeshis abandoned the Pakistani state because they saw themselves as Bangladeshis first then as Muslims.
-Pakistan was founded as a separate homeland for the Muslims if not Islam why not become a part of India?
To answer the first argument, the reason why the Bangladeshis chose to gain independence from Pakistan was not because of their alleged un-Islamic sentiments, but because they felt they were being cheated (as do many ethnic minorities of Pakistan today) along linguistic and cultural rights. They resented Undri (or Urdu) being the national language at the expense of their native Bengali.
In addition their political rights as Pakistani citizens were neglected such as the lack of presence of Bengalis in the Pakistani military.
The tension between the Bengalis and the Pakistani state reached a climax when the victory of the Awami league in the elections was not respected.
After all this unfair treatment, the Bengalis revolted. It had nothing to do with their preference of ethnicity over religion.
Additionally Bengalis are much more different to the rest of Pakistan culturally, geographicly and racially. Not that it makes them "inferior" or "less worthy" but it makes no sense in being once state especially with a giant enemy in between always adding more to the problem.
To answer to the question if not for Islam why 'create' Pakistan in the first place?
This question is based on alot of misconceptions. Firstly the Pakistan region or the Indus region was never a 'part' of a country called 'India' which never really existed.
The name "India" was brought by the British to Southern Asia and imposed into the local population. It was the British who unified this multi-cultural, multi-lingual, multi-ethnic region into one single state.
Even today this country calling itself "India" has no common identity be it linguistic, racial, cultural or religion.
The nation of Pakistan has existed for atleast nine thousand years from what records show . The Indus valley Civilization spread over most of Pakistan. It's nationhood can be evident even further as it's main cities spread over various provinces of the country as the map above shows.
Indeed Pakistan is a very unique country for it's region and most of the world. It's people lived share a common ancestry and lived together for thousands of years. They speak closely related languages almost all belonging to the Indo-Iranic subfamily of Indo-European. In addition they have caucasianoid skulls and common R1A genetic markers (with Kashmiris having the highest percentage of R1A genes) all evidence of a common ancestry.
The same cannot be said for other country's in the region such as Iran, Iraq, Afghanistan and especially India.
India is one of the last countries in the world to see itself as a single-identity state. It's people do not have a common language family. The main language families in India are Indo-European, Sino-Tibetian, Austro-Asiatic, Dravidian- all unrelated to one another as far as linguists can tell.
The people today known as "Indians" are also racially diverse. Though they have mostly Caucasianoid skulls like Pakistanis, a large and very significant percentage of the have Mongoloid skulls particularly in the north Eastern areas. Also Australoid skulls can be found in the southern areas of the country.
So to conclude it all "Indians" are no more of a people than "Americans" or "Canadians."
Coming back to the myth of Islam being the unifying factor- it is clearly false. The people of Pakistan lived together for thousands of years prior to the arrival of Islam. They share a common ancestry as do the languages they speak today.
As stated in an earlier post, even the non-Indo-European speaking populations; the Hunza, the Brahuis, the Baltistanis do not stand out much genetically.
This is more than enough reason to unify the country without bringing in religion.
If Islam is everything what Pakistan is about why was Jinnah then a secular man then?
The answer comes back to the same conclusion, Islam is not a unifying factor for Pakistan or it's identity.
Let's also not forget the British opposed the idea of Pakistan becoming an independent state, contrary to what is falsely preached by many.
The British wanted a single puppet state that they could use as a proxy in the region as opposed to having to deal with multiple states.
There are differences between Pakistani tribes and ethnicities. This is the process of evolution. Cultures, races, languages evolve due to independence from one another. But the similarities are far greater than the differences.
But those who blindly chant that Balochis, Sindhis, Punjabis, Pakhtuns, Kashmiris are all different are illiterate in the fields of linguistics, anthropology and race and should not be taken seriously.
Mistrust exists between Pakistani ethnicities due to political imbalance which is wrongly dominated by the Punjabi population. It is not because one is slightly culturally and linguistically different from the other.
And it's these imbalances that should be dealt with through justice, not by highlighting minor differences between Pakistani ethnicities or imposing religion on the state and the masses.