Why was India partitioned into two other countries

The two-nation theory was a founding principle of the Pakistan Movement (i. e., the ideology of Pakistan as a Muslim nation-state in South Asia), and the partition of India in 1947 ... It means a clear partition of India into a Muslim India and a non-Muslim India.

The British officials partitioned India into India and Pakistan because they wanted to ensure a safe and secure region. In what way did Pakistan also undergo a partition? Pakistan also underwent a partition when it split back into and fought each other as East and West Pakistan.