First, from the report, an essential definition:
For the purposes of the survey, a “biblical worldview” was defined as believing that absolute moral truth exists; the Bible is totally accurate in all of the principles it teaches; Satan is considered to be a real being or force, not merely symbolic; a person cannot earn their way into Heaven by trying to be good or do good works; Jesus Christ lived a sinless life on earth; and God is the all-knowing, all-powerful creator of the world who still rules the universe today. In the research, anyone who held all of those beliefs was said to have a biblical worldview.
The same questions were asked of respondents in national surveys by Barna in 1995, 2000 and 2005. The results indicate that the percentage of adults with a biblical worldview, as defined above, has remained unchanged for more than a decade. The numbers show that 7% had such a worldview in 1995, compared to 10% in 2000, 11% in 2005, and 9% now.