In no democracy, law is applied differently to different religions. However, may be due to bitter inter-religion relation during partition, Constitution makers might had allowed both Hindu Marriage Act and Muslim Personal Law Boards etc. During Saha Bano verdict, there was a chance of moving forward with uniform civil code, but Rajiv Gandhi government reversed the verdict with a constitutional amendment scaring of Muslim vote bank.
However Article 370 doesn't deal with any religion. Rather it deals with India's relation with the State of J&K. Thus it's a national issue and never a religious or social issue! Dr. Shyama Prasad Mukherjee had first demanded elimination of this article and there after it's a BJP demand. Because some see BJP as a communal party, all demands by BJP can't be communal.
What's article 370? Let's briefly discuss its existence and specialty.
Article 370 made operative from 17th November 1952 as per the Instrument of Accession of the state of Jammu and Kashmir to the Union of India. According to this article except for Defence, Foreign Affairs, Finance and Communications, (matters specified in the instrument of accession) the Indian Parliament needs the State Government's concurrence for applying all other laws. Thus the state's residents lived under a separate set of laws, including those related to citizenship, ownership of property, and fundamental rights, as compared to other Indians.
Although similar unique protections exist in tribal areas of India including those in Himachal Pradesh, Arunachal Pradesh, Andaman & Nicobar Islands and Nagaland, But article 370 has unique importance because it deals with the state of Jammu and Kashmir & the accession of the state to India is still a matter of dispute between India and Pakistan.
Thus Article 370 makes J&K a state having its own constitution, no law passed by Parliament can be applied in that state without concurrence of the J& K assembly. Rest of India can't have citizenship, purchase property. Even a Kashmiri girl married a person belong to other state will lose Permanent Residency status in J&K. This PR issue was in fact raised in J&K high court in the case of State of J & K Versus Sheela Sawhney, where High Court ruled that after marriage Kashmiri women's PR status will remain intact.
Post this verdict, and the then chief minister Mehbooba Mufti introduced a bill in J&K assembly 'Permanent Resident's Disqualification Bill, 2004'. This bill was passed with the support of PDP's rival national conference in order to reverse the verdict, although the bill is yet to promulgate.
Now the pro-abrogation of Article 370 logic is, how can J&K can be India's integral part as Article 370 differentiates the state from rest of India? The laws applicable in rest of India can't be applied there be it be anti-corruption bill, RTI or any other bills until J&K assembly gives concurrence. This was the State would remain more alienated from the rest of India. How can a states assembly has right to reject a law passed in Indian Parliament?
Again article 370 is always temporary in nature. When constitution is amended around 100 times, why this can't be deleted as an amendment? The logic that the guarantee given during accession should be honored & can't be changed fall flat because all other guarantees given to other kingly states during accession already reversed such as Privy purse to the Kings & their inheritors. Isn't article 370 making as if a different country tied with India through a diplomatic treaty? As early as in 1963, Nehru too realized that article 370 should be abolished. He said then "Article 370 has been eroded, the process of gradually erosion is going on; we should allow it to go on." According to Arun Jaitely, article 370 is discriminatory & there is no place of discrimination in any law!
The opposing group claims that it's article 370 which in fact hold J&K in India. The article 1 of J&K Constitution says that J&K is an integral part of India. Any attempt to delete the article will increase the resentment among the Kashimiries which may go out of control. In fact Shekh Abdulla realizing the temporary & transitional nature of this article, demanded iron clad guarantee on the existence of this article, to which government of India didn’t agree. Being aggrieved he demanded independence of J&K for which he had been jailed in 1953. Thus similar situation may arise. Moreover in some other states also there is a limited citizenship, why focus on Kashmir.
From the above it's clear that both sides have some strong points. Modi might have his own agenda, but his demand for debate is very genuine. It's definitely a national issue. If we stop refereeing this issue as a sacrosanct one & unutterably, then we must be doing a great disservice to the nation & playing with the national interest. Many think that article 370 is benefiting Pakistan's claim. Thus one may not demand abolishing the article immediately but what’s wrong in debating it in depth?