According to Wikipedia, the majority of Czechs are
atheists. Only 10% are Catholics (1) and there is a reason for that:
"Ever since the 1620 Battle of White Mountain, the Czech people have been historically characterised as "tolerant and even indifferent towards religion"."
"Pew Research Center found in 2015 that 72% of the population of Czech Republic declared to be irreligious"
Also (2):
"With the fall of the Habsburgs in 1918, more than a million Czechs (including 300 priests) left the Roman Catholic Church. Most chose not to affiliate with another church."
Why such a reaction? In (1) we read how the Catholic Church and the rulers behaved before, under the Habsburgs control:
"the whole population was forcibly converted to Roman Catholicism—even the Utraquist Hussites. All kinds of Protestant communities including the various branches of Hussites, Lutherans and Reformed were either expelled, killed, or converted to Roman Catholicism."
Also (3)
"Royal decrees pertaining to religion granted Protestant lords, knights, and burghers the right to choose either conversion or emigration. Only about one-quarter of the noble families living in Bohemia and Moravia prior to 1620 remained"
"The emigrations devastated Bohemia and Moravia, which may have lost as much as one-half of their population."
Then in 1781 Joseph II "abolished restrictions on the personal freedom (serfdom) of the peasants, and he granted religious toleration."
1) https://en.wikipedia.org/wiki/Religion_in_the_Czech_Republic
2) https://fee.org/articles/how-state-religion-made-the-czechs-...
3) https://www.britannica.com/topic/Czechoslovak-history/The-Co...