The law is short and the doctrine built on it is not. Two clarifications are worth making because both are widely misread outside France.
Laicite is not a rule about citizens. The obligation of neutrality falls on the state and on its agents: a public servant may not display religious affiliation in the exercise of the office, and the public authority may not endorse a religion. Private persons retain the free exercise the first article guarantees, and the law of 1905 imposes no dress rule, no speech rule and no restriction on public worship. Later statutes have done so in specific settings, notably the 2004 law on conspicuous religious signs in state schools and the 2010 law on concealing the face in public, and those are separate instruments with their own histories.
Nor is the separation uniform across the territory. Alsace and the Moselle were annexed by Germany in 1871 and did not return to France until 1918, by which time the 1905 law had passed without applying to them. The Concordat regime continued there and continues today: clergy of the recognised religions are paid by the state, and religious instruction is provided in public schools. Guyane operates under a different arrangement again.
The law also required an inventory of church property, and the inventories of 1906 produced riots and at least two deaths. Jean Bauberot has traced how the settlement moved from that conflict to something close to consensus over the following decades.