According to the discussion of civil liberties, what is "intelligent design"?

"Intelligent design" proponents say that the universe and life on earth are so complexly arranged that they could not have evolved that way on their own, but that there must be a supernatural entity of some form that designed life and the universe.

This has become a debate over civil liberties, with religious adherents seeking to have intelligent design taught alongside evolution theory in public schools, and groups like the American Civil Liberties Union (ACLU) arguing that religious beliefs do not belong is a public science classroom. Note that the ACLU is not taking a position against religious belief per se, but saying  that "intelligent design" is essentially another term for creationism and religious belief, and thus is not a scientific approach.  In Kitzmiller v. Dover Independent School District, a case tried in district court in Pennsylvania in 2005, the court agreed with the ACLU's position.  Along with the ACLU, the Dover Independent School District was also represented by the Americans United for Separation of Church and State.

Southern secession is the event or issue that historians can gain insight from this excerpt.