Short answers, pulled from the story.
Secularism is the principle of conducting human affairs based on naturalistic considerations, uninvolved with religion. It is most commonly thought of as the separation of religion from civil affairs and the state. It concerns minimizing religion's role rather than disproving it, and may be hostile, neutral, or hospitable to religion.
The British agnostic writer George Holyoake first used the already-existing word secularism in a modern sense in 1851 in Britain. He found atheism too aggravating and wanted a term describing a stance based on naturalistic considerations without necessarily rejecting religion.
There are distinct traditions of secularism, including the French, Turkish, American, and Indian models. They differ greatly, from the American emphasis on avoiding an established religion and freedom of belief, to the French interventionist model. In India secularism does not completely separate state and religion, while in France it precludes such mutual involvement.
After Mustafa Kemal Ataturk rose to power in 1923, Turkish secularism, or laiklik, became a state ideology under Kemalism, aiming to modernise the country. It was initially modelled after French laicite, and Turkey remains virtually the only Muslim-majority nation with an effective secular government.
India became a secular state after it achieved independence in 1947. Mahatma Gandhi supported pluralist secularism as a means to curb tensions in the religiously diverse nation, and the Indian model stressed equality of citizens before the law regardless of faith.
The frameworks include separationist secularism, which enforces the separation of church and state, and laicite, the French framework giving the state legal supremacy over religion. Accommodationism actively supports religion in general without favouring a sect, as in India, while state atheism is a total ban on religion typically associated with Marxism and Communist states.
Secularism's origins can be traced to the Bible itself and were fleshed out throughout Christian history into the modern era. The Christian church has had secular clergy since the medieval period, and theologians such as St. Augustine, William of Ockham, Martin Luther, and John Locke contributed to principles used in modern secularism.