In the seventeenth century, Europe and particularly Germany was convulsed by the thirty year war. Contiguous small kingdoms of Catholic Christians fought the Protestant ones with enormous death tolls and destruction. Intra-protestant civil war led to the beheading of Charles the first in Britain. Prior to that Henry the eighth desirous of a remarriage to obtain an heir, had disavowed the Pope and founded the Church of England with the monarch as the head of the new religion, a practice still prevalent there. In much of Europe in the earlier centuries, the population was coerced to follow the king's religion with persecution of the minority religionists. This led to discrimination against the Catholics in England, the Huguenots in France, the expulsion of Jews and Muslims from Spain and even the Portuguese inquisition against Hindus in Goa.
After the Treaty of Westphalia that ended the thirty year war, some tolerance of minority Christian religious sects began. It must be noted that powerful kings often ignored their own co-religionist kings and fought against them for political reasons as some Muslim chiefs did against Akbar and with Rana Pratap in India. While there are unforgivable sins of slavery and colonial exploitation on the report card of the West, they have generally achieved a civilization and culture of tolerance and freedom of religion and uniform civil laws for all citizens with no discrimination between religions other than symbolic. Presently in America, the Congress deliberations begin with a Christian chaplain's prayer and oaths in courts are sworn on the Bible.
There should be no separate inheritance, marriage or divorce laws for each religion and no state subsidies for religious pilgrimages. John Rawl's theory of justice can best be summed up by making the cutter of the cake carve out as many pieces as there are persons and letting them exercise their choice first, while the cutter willingly accepts the remaining last piece.
Once the state favors one religion, conflicts arise and even more so when that religion punishes apostasy by death.
Everyone may have heard of the case of the Afghan born Muslim who converted to Christianity and was sentenced to death by its court and was spirited away to Italy which granted him political asylum. Now there is the case of the Malaysian woman born Muslim who wishes to convert to Christianity to marry her Christian fianc' and the Malaysian Supreme Court has refused her permission and referred the case to the Islamic religious authorities. Before that a Hindu Malaysian was denied cremation after death despite his wife's wishes because there was some doubtful evidence of his conversion to Islam.
The other side of the coin is the bribing by Christian and Islamic missionaries to convert poor and Dalit Hindus in India. Legally, this should not be prevented as it is the choice of the individual to barter religious affiliation for monetary gain, but when a pseudo-secular state like India has a belligerent religious state like Pakistan as a neighbor sanctifying Islam, a religion that emphasizes allegiance to the Ummah above the nation, this individual freedom can lead to the demise of the state by fifth columnist traitors. The very birth of Pakistan can be attributed to religious reasons and is the source of terrorism in Indian Kashmir and Punjab. On the other extreme, the oppression of Palestinians by a Jewish state like Israel and the treatment of its own Muslim citizens as second class is not acceptable either.
The survival of a nation state takes precedence until such time as there is totally free movement of people across boundaries and we achieve 'Vasudhaiv Kutumbakam'. The pragmatic corollary that can be derived is that no nation can have laws that allow forced or bribed conversions particularly if they have a belligerent religious state as a neighbor and an enemy. It is equally imperative for it to bite the bullet and dismantle religion based civil codes. Even the tolerant west has woken up after Islamic terrorism in Spain and Britain and the EU and America are now worried about the loyalties of their increasing Muslim minorities, though doing little to alleviate their xenophobic racism or aggression towards distant oil rich Muslim nations whose oil and gas they badly covet and wish to control. The newest battle is between Sunnis and Shias all over the Middle East.
Ethnic groups divided amongst neighboring nations promote fissiparous inclinations. India's insurgencies in the northeast are classic examples. The Albanians in Kosovo, the dissolution of Yugoslavia and the Soviet Union can be ascribed to ethnicity as well as politics and economics. Conflicts between the Kurds and Turks, various tribes in African nations, Basques in Spain and previous ones in Belgium, Tamils in Sri Lanka and the Karen in the golden triangle of Myanmar are all examples of unremitting ethnic strife and violence. Once again national policies need to be inclusive and uniform across regions to convince such groups that they are stakeholders and active participants in progress and division of the whole pie.
Last but not the least, any belief that lays down theological straitjackets that constrain individual freedom is incompatible with democratic rule and progress. Islam falls into this category and wishes to exercise the tyranny of the majority where it is in a majority, but unwilling to tolerate the same when it is in a minority and thus will always lead to stunted human development quotients until it achieves a reformation and renaissance which are unfortunately incompatible with its key tenet that its scriptures are the word of God and immune to popular will or rational interpretation.