Muslim thought in India can be thought of as having two lineages

1. Islamic puritanism

Lineage : Sirhindi -> Shāh Walīullāh ->Syed Ahmad Barelvi, Deobandi movement, Maulana Azad -> Jamaat e Islami

2. Muslim nationalism

Syed Ahmed Khan ->Jinnah, Iqbal - > Ayub Khan/Musharraf

The former originated largely as a religious movement.

It has its origins in Sirhindi, who voiced the view in 16th cen, that Akbar's policy was "Indianizing" Islam too much

Too much of Din-e-ilahi crap.

Let's keep Islam pure

That lineage continues in the thinking of 18th cen theologian Shah Waliullah , the Delhi based Islamic scholar who lived b/w 1703 and 1762

Waliullah like Sirhindi emphasized segregation/purity
and loyalty to the Ummah (the global Islamic whole)

Not to South Asian muslims per se

Waliullah once said

"Muslims, no matter where they live, they should be completely separated from the natives of that country in their culture, traditions and mannerisms. And wherever they are, they must be immersed in their Arabic splendor and Arabic trends”

This line of thinking continues in two 19th cen movements-

That of Syed Barelvi - who fought valiantly against Sikh rule in Punjab at Balakot

And that of the Deobandis in late 19th cen

The Khilafat movement's Ali brothers could be said to belong to this lineage

As well as figures like Maulana Azad and movements like Tablighi Jamaat

For them, the global muslim causes mattered more than South Asian muslim fortunes

So someone like Maulana Azad opposed Partition of India, because that would mean splitting the South Asian muslims into two. Not ideal

For the same reason, even Jamaat e Islami opposed Partition back in the 1940s. So did the Deobandis (if I am not wrong)

The modern Jamaat in Pakistan, and also fringe groups like AIMIM in India represent this school in South Asia today.

Emphasizing Islamic fundamentals. Not necessarily Muslim secular interests in South Asia

The other great branch in Muslim thought is more secular in character

This originates as late as 19th century in the figure of Syed Ahmed Khan

He was a "muslim modernizer", who supported the British in 1857

His obsession was more with "muslim interests" in South Asia. What will happen to Muslims in a Hindu majority subcontinent?

He did not think of Partition. But was focused on short run fortunes of Muslims in the wake of the great 19th cen Hindu ascendancy in civil services etc

He advocated even co-operation with the British, for this end, as he thought the Abrahamic and beef-eating Brits to be closer to Muslims in spirit than the Hindoos

He was not a fundamentalist, but a modernizer albeit religious

In his lineage, we have a different set of figures

People concerned with Muslim demographic in South Asia, and economic interests of Muslims

Not with Islamic purity per-se

In this branch we encounter Jinnah, the great Iqbal, Rahmat Ali, and men of that ilk.

You could say the military figures of Pakistan - like Ayub Khan, Yahya Khan, Musharraf represent this intellectual branch.

Now how does all this relate to the idea of Pakistan

We need to be clear that Pakistan as an idea emerged from the "Syed Ahmed Khan" branch. Not the tradition of Sirhindi / Waliullah

Syed Ahmed may not have thought of it. But it became a major agenda item for figures like Jinnah / Iqbal in early 20th century

Particularly after the great electoral setbacks of the mid-30s when Congress swept elections across the country

Today, Islamic revivalism / puritanism of the type that originated with Sirhindi 400+ years ago is represented in both India and Pakistan

But the Muslim nationalism of the type that emerged under Jinnah / Iqbal largely exists in Pakistan

Not so much in India

Both branches shared several things in common

For one thing - a strong antipathy towards Hindus

But the solutions were different in either case

The Islamic puritans were not BIG on partition
They preferred social segregation within an Indian federation

The Muslim nationalists, in contrast, were not content with segregation. Being more ambitious, they feared Hindu dominance in secular spheres

Hence the call for Pakistan

Post-script :

A minor clarification - When I referred to Syed Ahmed Barelvi, I was merely referring to his person, and his importance in the history of islamic revivalism / jihad

Not to the Barelvi movement within Islam that has little to do with Syed Ahmed Barelvi