What is the definition of Creationism?

Websters writes:cre”a”tion”ism n : a doctrine or theory holding that matter, the various forms of life, and the world were created by God out of nothing ” cre”a”tion”ist \-nist\ n or adj

WorldBook1999 writes:Modern Christian creationist belief stems from a time line published in the 1650's by James Ussher, an archbishop of the Church of Ireland. Ussher constructed the time line by interpreting literally the birth and death dates of figures in the Bible.
According to Ussher, God created the earth and its life forms in 4004 B.C. Today, however, considerable disagreement exists among creationists concerning the date of what they believe was the Creation.In the 1700's and 1800's, Ussher's ideas were called into question by the theory of evolution and other scientific developments. Christian leaders argued increasingly among themselves about the role of science in understanding Biblical accounts of the Creation. Some maintained the Bible should still be the basic source for information on the origin of the earth and its life.In the early 1900's, public high schools in the United States began teaching evolution in science classes. In the 1920's, creationists proposed laws in 20 states to ban public schools from teaching evolution. They considered the teaching of the theory to be part of a dangerous trend toward the separation of religious beliefs from everyday life. Several states, including Arkansas and Tennessee, passed such legislation.The American Civil Liberties Union (ACLU) opposed the laws, saying that they violated the constitutional principle of the separation of church and state. The ACLU challenged the Tennessee law in 1925 by defending a teacher named John T. Scopes, who had volunteered to stand trial on the charge of teaching evolution.The ACLU lost the Scopes case, and the laws against teaching evolution remained in effect. However, public opinion of creationism suffered as a result of the trial because the press portrayed creationists as uninformed and out of touch with mainstream science.In the 1960's, more public schools again began to teach evolution, in part because of a fear that the United States was falling behind other nations in the teaching of science. In 1968, the Supreme Court of the United States ruled that laws banning the teaching of evolution were unconstitutional because they made religious considerations part of the curriculum. Despite these setbacks, the creationist movement gained strength in the 1960's.In the 1970's and early 1980's, scientific creationists proposed laws that would have made creationism a required subject in classrooms that taught evolution. These people argued that creationism, like evolution, is based on science and so should be taught along with evolution. They also said that because evolution is "just a theory," it should be considered a religion. Thus they claimed that teaching only evolution would violate the Constitution both by limiting academic freedom and by supporting one religion over another..