This is a good question and one that is greatly debated today. We can say that it is one of the hot button topics of our time. Here are some points that you need to consider.
First, most of the world teaches the opposite of creationism. They teach evolution. Moreover, there is little controversy. However, in the United States, in some areas, some people are not happy with a theory of evolution, because they believe in creationism on account of their faith in the Bible. Many conservative Christians espouse a theory of creation.
Second, the Supreme Court has ruled that it is unconstitutional for teachers to teach creationism in school. The reason for this is the separation of church and state.
Third, some people want to use the idea of intelligent design, as a middle way. The lower courts ruled against this, but there is still a great debate.
"Evolution is a fact, not a theory. It really worked." - Dr. Carl Sagan