First, there are some Christians who have a weak view of the inspiration of Scripture as revealed by God. As a result they feel that some of the Bible is legend, has errors, and does not need to be read literally (especially Genesis). These are the people who often take the most interpretational liberties with Genesis, and their origin theories are viewed by others as compromising the doctrine of inspiration and Christian theology.
Second, Christians disagree whether the first chapter of Genesis is history or myth. If it is myth, then we cannot hope to derive any historical or scientific information from the biblical creation account, and facts concerning creation must be derived only from science. If it is history, and we believe in inspiration, then we understand creation to be in six days, to include a literal Adam and Eve and a historical global flood that laid down the rock strata of geology in recent times.
Third, there are many Christians who have not been diligent to study either the biblical account of creation or the scientific data. They don’t base their views on evidence. Rather, they just want “peace” between Christians and science. As a result, they are willing to compromise what they think and say in order to just get along.