Secularism is the principle of the separation of government institutions and persons mandated to represent the state from religious institutions and religious dignitaries (the attainment of such is termed secularity). One manifestation of secularism is asserting the right to be free from religious rule and teachings, or, in a state declared to be neutral on matters of belief, from the imposition by government of religion or religious practices upon its people. Another manifestation of secularism is the view that public activities and decisions, especially political ones, should be uninfluenced by religious beliefs or practices. 

Secularism draws its intellectual roots from Greek and Roman philosophers such as Epicurus and Marcus Aurelius; from Enlightenment thinkers such as John Locke, Denis Diderot, Voltaire, Baruch Spinoza, James Madison, Thomas Jefferson, and Thomas Paine; and from more recent freethinkers and atheists such as Robert Ingersoll, Bertrand Russell, and Christopher Hitchens. 

The purposes and arguments in support of secularism vary widely. In European laicism, it has been argued that secularism is a movement toward modernization, and away from traditional religious values (also known as secularization). This type of secularism, on a social or philosophical level, has often occurred while maintaining an official state church or other state support of religion. In the United States, some argue that state secularism has served to a greater extent to protect religion and the religious from governmental interference, while secularism on a social level is less prevalent.
Are they Greek and Roman philosophers?
Secularism draws its intellectual roots from Greek and Roman philosophers