When India was divided, prime minsters of India and Pakistan [Liaquat–Nehru Pact] agreed on treating their respective minorities well. Without this agreement the minorities[Hindus, Sikhs etc in Pakistan] living in each country could have choose to move to the other[India in this case].

Hence passing CAA is just accepting the fact that Indias neighbors are not treating minorities well as they promised and delivering the promise that was made during independence.