When did the secular worldview begin?

Atheism has been advocated by various intellectuals for over two thousand years, and quasi-secular philosophies have been in development and practiced for the same amount of time. Such things appear to have begun under the pre-Christian Greeks, then continued under the Romans, and then were suppressed by Christian violence and intimidation until the Enlightenment (in 17th-18th century Europe and America). The secular worldview has grown and improved and diversified since then and is flourishing now in all Western democratic nations.