Although Ibn Rushd (d. 1198 AD) is arguably considered the father of the secular thought in Western Europe, the term ‘Secularism’ was coined by an Atheist English Writer, George Jacob Holyoake in 1851, as a replacement of the then negatively perceived term ‘atheism’. Ibn Rushd put forth the idea that there are at least two paths to reach the Ultimate truth, i.e. Philosophy and Religion, implying that one can find the ultimate truth without necessarily resorting to Religion. On the similar lines, Holyoake sought to promote a social order separate from religion, without actively criticizing or dismissing the religious belief itself.
The phrase “separation of church and state” can be traced back to a letter written by Thomas Jefferson in 1802 to Baptists from Danbury, Connecticut, referencing the First Amendment to the United States Constitution. The letter says: “Believing with you that religion is a matter which lies solely between Man & his God, that he owes account to none other for his faith or his worship, that the legitimate powers of government reach actions only, & not opinions, I contemplate with sovereign reverence that act of the whole American people which declared that their legislature should ‘make no law respecting an establishment of religion, or prohibiting the free exercise thereof’, thus building a wall of separation between Church & State”. According to the first Amendment of the United States Constitution, “Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof…”.
As far as the establishment of religion is concerned, the Quran says, “He (Allah) has ordained for you all, the same System of Life that He enjoined upon Noah – And We have revealed to you (O Muhammad) the same Message as We enjoined upon Abraham, Moses, and Jesus: ‘Establish the Divine System of Life (in which the obedience is only to Allah’s Law or Command) and make no sects in it’.” The Quran also says that those who do not judge or rule according to what Allah has revealed are the Disbelievers. It is clear from the Quran that when the Believers/Muslims gain power in the land, it is incumbent upon them to establish the Divine Code of Life instead of the secular system.
As far as free exercise of religion is concerned, the Quran says categorically that “There is absolutely no compulsion or coercion in (opting for a particular) Deen (or a way of life or a system of beliefs and actions)”. The Quran also warrants full security and protection for the places of worships of all religions.
In short, while on one hand the Quran make it incumbent on the Believers to establish the Divine code of life for them and not a secular system, on the other hand it guarantees full freedom to the followers of all the other religions to follow their religion in their personal lives, and also provides security and protection for their places of worships.
 Holyoake, G.J. (1896). “Origin and Nature of Secularism”, London: Watts & Co., p.50.
 Al-Quran Surah 42: Verse 13
 Al-Quran Surah 5: Verse 44
 Al-Quran Surah 24: Verse 55; Surah 22: Verse 41
 Al-Quran Surah 2: Verse 256
 Al-Quran Surah 22: Verse 40