It is an enormous problem, as the 20th century saw the worst persecution of Christians since Roman times. For instance, millions of Orthodox believers perished in purges by atheists in the former Soviet Union. In the anti-Christian campaign by Stalin and Soviet communism, many churches were closed, and monks were arrested and deported to labor camps. As many as 40,000 Orthodox priests were killed or died from abuse during the first half of 1936 alone, and it is believed that the total number of priests, monks, and nuns killed during the purges of the 1930s are in excess of 200,000 (Foreset, 1997, pp. 134-149; Wynot, 2004). Estimates of the total number all Christian martyrs in the former Societ Union are about 12 million. Estimates from the 20th century of Christians who died from secular antireligious violence worldwide are over 25 million, more than all previous centuries combined (Bergman, 1996).
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The French Revolution, particularly in its Jacobin period, initiated one of the most violent episodes of anti-clericalism in modern Europe; the new revolutionary authorities suppressed the church; destroyed, desecrated and expropriated monasteries; exiled 30,000 priests and killed hundreds more.[2] As part of a campaign to de-Christianize France in October 1793 the Christian calendar was outlawed, replaced with one reckoning from the date of the Revolution, and then an atheist Cult of Reason was inaugurated, all churches not devoted to that cult being closed.[3] In 1794, the atheistic cult was replaced with a deistic Cult of the Supreme Being.
http://en.wikipedia.org/wiki/Anti-clericalism
Following the Mexican Revolution of 1910, the new Mexican Constitution of 1917 contained further anti-clerical provisions. Article 3 called for secular education in the schools and prohibited the Church from engaging in primary education; Article 5 outlawed monastic orders; Article 24 forbade public worship outside the confines of churches; and Article 27 placed restrictions on the right of religious organizations to hold property. Most offensively to Catholics[citation needed], Article 130 deprived clergy members of basic political rights. Many of these laws were resisted, leading to the Cristero Rebellion of 1927–1929. The suppression of the Church included the closing of many churches and the killing of priests. The persecution was most severe in Tabasco under the atheist"[26] governor Tomás Garrido Canabal.
The war had a profound effect on the Church. Between 1926 and 1934 at least 40 priests were killed.[27] Between 1926 and 1934, over 3,000 priests were exiled or assassinated.
http://en.wikipedia.org/wiki/Anti-clericalism
La Violencia refers to an era of civil conflict in various areas of the Colombian countryside between supporters of the Colombian Liberal Party and the Colombian Conservative Party, a conflict which took place roughly from 1948 to 1958.[33][34]
Across the country, militants attacked churches, convents, and monasteries, killing priests and looking for arms, since the conspiracy theory maintained that the religious had guns, and this despite the fact that not a single serviceable weapon was located in the raids.
http://en.wikipedia.org/wiki/Anti-clericalism
The Civil War in Spain started in 1936, during which thousands of churches were destroyed, thirteen bishops and some 7,000 clergy and religious Spaniards were assassinated.[43] Catholics largely supported Franco and the Nationalist forces in the Spanish Civil War of 1936–1939.
Anti-clerical assaults during what has been termed by the Nationalists Red Terror included sacking and burning monasteries and churches and killing 6,832 priests,[44] including 13 bishops, 4,184 diocesan priests, 2,365 members of male religious orders, among them 259 Claretians, 226 Franciscans, 204 Piarists, 176 Brothers of Mary, 165 Christian Brothers, 155 Augustinians, 132 Dominicans, and 114 Jesuits.
One source records that 283 nuns were killed, some of whom were badly tortured.[45] There are accounts of Catholic faithful being forced to swallow rosary beads, thrown down mine shafts and priests being forced to dig their own graves before being buried alive.
http://en.wikipedia.org/wiki/Anti-clericalism