The main reason used by Nehru for keeping India secular was to maintain the unity of the country. He believed that by making any religion the offlicial religion we wont just undermine the religious identities of the minoritie but it may also lead to conflicts and further divisions. He believed the all minorities, especially Muslims who were in such a large number, must be given security and the rights of citizens in a democratic State. The reasons to do so were not just ethical and sentimental but also prudential as he felt that if thye failed to deal with the minorities in a civilized manner, the country's whole body politic would be poisoned and probably destroyed. It was in the best interest of the country that he wanted to keep India secular.