You can be against religion but your example with the kuffiyeh is a bad one because it’s a nationalistic symbol that is worn by Palestinians of any religion (or thereby lack of) plus their supporters.

Those familiar with French society and the debates over the Hijab in many European countries also know that laicism or any other secularist laws are usually abused by conservative politicians as a masquerade to introduce discriminatory laws against Muslims.

Especially French lawmakers are notorious in this aspect. As another commenter already mentioned, Christians wearing a cross usually don’t have any issues.

Belgium as in this case is also not much better in this aspect even though I’m not aware they have a laicist state philosophy.