In Japan, it was once forbidden to have ideas different from the majority.
In Japan, people used to be prohibited for having ideas that differed from the country's ideal.
日本では = in Japan
禁じられていた = (it) was forbidden / (it) was prohibited / (it) wasn't allowed
思想を持つ = to have thoughts / to have ideas / to think
国と違う = different from a country('s ideas, majority, values, traditions) / different from the majority (of a country) / differ from
People weren't allowed to have thoughts different from what they were told to think. はもう一つの言い方です。hiroさん、の言たいことは、一つの言い方があるではない。いろいろな文がつくることが出きる。一番言いやすいの方を選んでくださいね。