Starting in 1933 NaziGermany had a program to secularize the German language. The Nazis themselves called it Sprachregelung (regulation of language). The Sprachregelung was mainly directed by the Reichsministerium für Volksaufklärung und Propaganda (RMVP) (Ministry for the enlightenment of the people and propaganda). While the RMVP concentrated mainly on controlling and censoring the language of the media and the language used in movies and other cultural ventures, there were other actions as well. The Nazi governement published a new dictionary, which contained only secularized language, that was in unison with the parties ideology. The sad culmination of the Sprachregelung was in the vocabulary for the Endlösung. Humans became units, murder became deportation etc.
George Orwell's 1984 describes how a tyrannical government changes language to entrench its power. This is done by the so called Newspeak. Newspeak is a slimmed down version of normal English. Its goal is to prevent the speaker forming thoughts like rebellion or dislike against the government or one of its leaders. Even if an individual would be able to form such thoughts, it would be impossible to communicate them to others using Newspeak. Orwell's description of newspeak was heavily influenced by the language controls of Nazi Germany and the Soviet Union.
While motivations will vary from from one individual to the next there is a degree to which the secularization of language may be driven by some Christians wanting to avoid breaking the Third Commandment. In what is sometimes described as a 'minced oath' a speaker, often under stress, begins to form a taboo term and then corrects himself with an acceptable term that rhymes or has a similar initial sound. Thus 'God' becomes 'gosh', 'golly' or 'goodness gracious'; 'Jesus' becomes 'gee' or 'jeepers creepers'; 'Christ' becomes 'crikey' or 'crumbs'. The taboo term may not have any religious connotations: 'shoot' and 'sugar' are used merely to avoid a vulgarity. The fact that words such as 'crikey' and 'gee' have become less prevalent in recent decades, to be replaced with the original 'Christ' or 'Jesus' may be as much down to a reduction concern about breeching the Third Commandment as it is to an increasing desire to reintroduce Christian terminology into everyday speech.
1 Sometimes C.E. is an abbreviation for "Christian era" instead of "common era", but this also conceals the historical basis due to Jesus Christ being Jewish. Christianity would not exist as a separate religion until much later.
2 The 'X' in "Xmas" was originally an abbreviation for the Greek letter "chi" translated as "Ch", though the abbreviation eventually became a means of "crossing out Christ".
3 Easter was originally a pagan festival, upon which Christianity would later apply the Resurrection of Christ and surrounding events (such as the Crucifixion on Good Friday). "Resurrection Sunday" is often used to emphasize the Resurrection of Christ rather than the pagan holiday.
4 Washington's Birthday was February 11th in the Julian calendar, while Lincoln's Birthday was February 12th in the Gregorian. Under the Gregorian calendar, Washington's Birthday would be February 22nd. Thus Washington's birthday would be more accurate. (source)
5 This was part of the original Pledge of Allegiance. "Under God" was added in the 1950s at the request of President Eisenhower. (source) However, atheists such as Michael Newdow have been trying to remove the phrase "under God" from the Pledge through the federal courts (source)
6Pro-choice people often use the phrase "birth control" regardless of whether conception has occurred.
↑All Hallow's Eve was originally the pre-Roman pagan Celtic holiday of Samhain's Day. In 835 Pope Gregory IV moved All Saint's Day, which celebrates the lives of Catholic martyrs and the communion of saints, to November 1. Thus, Halloween is not itself a Christian holiday, but the evening before the Catholic feast day.