The rule book is constitution which governs the way every citizen of our country should work in social harmony with others. All other books are below it. Simple.
People are free to observe what ever religion they want to follow till it is behind door and not hurting others (others can be of same religion or different religion). Also, if anything in the religion is causing widespread injustice then the government of the day has to act along with other constitutional institute to ensure the cause does not lead to law and order situation and no human values are lost.
Same is the case with triple talaq. This evil practice which is being abandoned by many muslims countries, should be abolished by India soon to end the misery of muslim women.
Funny part is they are defending on the topic which their own government has abolished many years back.
These internet warriors Pakistanis are way behind time and out dated with their knowledge.