My grandparents were born in a de-facto theocracy that was only overturned in the early 60s. We call the years that came before it les années noires (the dark years) for good reason. Attrocities were commited in God's name and people were kept poor and suffering. Without the Church rule we are now free to pursue higher education, run businesses, women aren't bullied at home every week by priests requiring they have kids until they die (my grand-mother was recovering from tuberculosis and the doctors were sure another kid would kill her, the priest reminded her every week it was her duty), and doctors don't have to defer to priests in life and death situations.

When you know the alternative, secularism and laïcité are the only viable options.