Laïcité is basically the French form of secularism. It is more ''aggressive'' than the typical secularism found in Anglo-speaking countries. The state takes an active approach to keep religion out of the ''public sphere'' and religion is seen something to be kept in the ''private sphere''. For example, in government buildings, people can't display overt religious symbols which also includes public schools. Right-wing critics of this claim the French government of making religion ''politically incorrect''.
I know the French attuide towards religion is very different from the American one, you'll have to change lot of things for this occur. In France, due to the French Revolution, where the modern ''French identity'' was created, religion was seen as a obstable to attaining more freedom and equal right. Religion had a certain reputation of almost being synonymous with feudalism among some circles.
What changes would America need to have such a stance?