Because the carnal mind is enmity against God:
"New polling data show that for the first time in a long time there’s a notable decline in the percentage of Americans — including Christians — who hold to the “Young Earth” creationist view that humankind was created in its present form in the past 10,000 years, evolution playing no part.
According to a Gallup poll conducted in May, the portion of the American public taking this position now stands at 38%, a new low in Gallup’s periodic surveys. Fifty-seven percent accept the validity of the scientific consensus that human beings evolved from less advanced forms of life over millions of years.
As the poll reveals, the biggest factor in the shift is a jump in the number of Christians who are reconciling faith and evolution. They are coming to see evolution as their God’s way of creating life on Earth and continuing to shape it today.
Tenacious anti-evolution resistance continues to influence debates over issues including public school curricula, government support for creationist installations like the Noah’s Ark replica in Kentucky, and research access to national parks. A creationist researcher, for instance, claimed religious discrimination in his successful legal fight with the U.S. Park Service over its refusal to grant him access to collect rock samples. His purpose: marshaling evidence in support of the creationist belief that the Grand Canyon was created by a great global flood a relatively recent 4,300 years ago — the same flood that Noah and company are said to have ridden out on the ark." USA Today