Belarus is a primarily Christian country. The Orthodox Church is considered the "official" church, and both Christmas and Easter are state holidays. Alexander Lukashenko, an atheist, boasts how no wars or conflicts have taken place in Belarus over religion.
Belarus was one of the core countries of the Soviet Union, a communist alliance of nations that brutally enforced atheism with the destruction of religious symbols and persecution of religious officials. Throughout the USSR's life, the Republic of Belarus was officially atheist.
However, Belorussian people have always been deeply religious, even from the days when Paganism dominated. And nowadays, Christianity is incredibly prominent within the country, Eastern Orthodoxy and Catholicism alone representing over 55% of the population. However, the 'official' status of Christian Orthodoxy does not only affect the Christian Orthodox practicers- for instance, many miners have deductions in their salary automatically going as a donation to the building of an Orthodox church. This mandatory donation is seen by some as repression of the freedom of religion, as everyone must comply to help build the Orthodox Church.
The lack of freedom of religion has been a common complaint against Belarus. Many groups must meet in secret or are persecuted by officers for having different beliefs. 41% of the country is even atheist, yet the ones who meet persecution are Christians of less popular denominations and people of non-Christian religions.
Anti-Semitism in particular is seen to be condoned by authorities. Multiple incidents of the defacing of Jewish tombstones have been overlooked or ignored by officials entirely.
Belarus has always been a religious community, throughout the Communist era and strict oppression.
Sources: Wikipedia, Forum 18.org, Index on Censorship.org, Belarus Guide.com