The Organization of Islamic Cooperation (OIC) is the world's second-largest inter-governmental organisation after the United Nations, with 57 member states from four continents. The OIC is the Muslim world's united voice, ensuring and safeguarding their interests in economic, social, and political arenas. The OIC has Institutions that carry out its programmes. Its headquarters are in Jeddah, Saudi Arabia.
The First Islamic Summit Conference, held in Morocco in September 1969, formed the Organization of the Islamic Conference to unite the Islamic world in the aftermath of an arson attack on the Al-Aqsa Mosque in Jerusalem by a 28-year-old Australian in 1969.
Article II (A) of the Charter states that the Organization of the Islamic Conference's objectives are:
to promote Islamic solidarity among Member States;
to consolidate cooperation among Member States in the economic, social, cultural, scientific, and other vital fields of activities, and to carry out consultations among Member States in international organizations;
to endeavour to eliminate racial segregation, discrimination, and colonialism.
to take the necessary steps to support international peace and security based on justice;
to coordinate efforts for the protection of the Holy Places and support for the Palestinian people's struggle, in order to help them regain their rights and liberate their land;
to support the struggle of all Muslim people in order to preserve their dignity, independence, and national rights;
to create an appropriate atmosphere for the promotion of cooperation and understanding among Member States.
Why is India not a member?
Due to Pakistan's manoeuvres, India was ejected from the 1969 first Summit of the Islamic Conference Organization in Rabat, Morocco, despite having been officially invited on the basis of possessing the world's largest Muslim population. Because of Pakistani treachery, the OIC has maintained a hostile relationship with India since then. A slew of one-sided and prejudiced OIC Resolutions on Jammu and Kashmir and the state of the Indian Muslim minority have been emphatically rejected by India.
India remained away for a variety of reasons, the most important one appears to be its a reluctance to join a religiously-motivated organisation. It could harm India's social stature of being a secular state, that maintains religious neutrality.
Furthermore, there is a possibility that strengthening bilateral ties with individual members being a member nation could put us under undue pressure in the grouping, particularly on matters like Kashmir. Regarding which OIC has been extremely vocal since its very inception.
That invitation was extended again at the 45th session of the Foreign Ministers' Summit in 2018, when Bangladesh, the host, proposed that India, home to more than 10% of the world's Muslims, be granted observer status, but Pakistan objected.
Somewhat it's India's reluctance and adding on to it is Pakistan’s constant objections and machinations. It has consistently blamed India for the Kashmir issue, and it seems that the OIC at times operates more like a tool in Pakistan's hands to criticise India and garner media from these false allegations.
The OIC is mostly dominated by Saudi Arabia, although Pakistan, as the only Islamic nation with nuclear weapons, has had a significant influence since its creation. As a consequence, the organisation has published various comments on Kashmir throughout the years that have been supportive of Pakistan and critical of Indian "atrocities." India being a Sovereign state does not appreciate any external organisation meddling in the internal affairs of the county. India has consistently underlined that J&K is an “integral part of India and is a matter strictly internal to India”, and that the OIC has no locus standi on the issue.
Organization of Islamic Cooperation (OIC) voiced "deep concerns" over the current hijab debate and "continued attacks targeting Muslims and their places of worship." India responded by accusing the OIC of functioning with a communal mentality and asserting that the organisation is still being controlled by vested interests to pursue their nefarious propaganda against India. India claims that the OIC is being influenced by Pakistan on matters such as Jammu and Kashmir and the alleged threat to Muslims in India.