Most Americans love football and faith. Mixing the two, NFL quarterback Tim Tebow has reinvigorated the debate about public expressions of religion.

One of the controversies has been the Denver player's common practice of writing biblical references--such as John 3:16--on the black marks beneath his eyes.

Yet, does the typical American even know what this reference means? Last year, theAmerican Bible Society commissioned Barna Group to find out how well Americans understood various aspects of the Bible, including if they could identify what the numbers "3:16" mean. The question mentioned the phrase John 3:16 and asked people to identify, without any predetermined choices, what the "three" means.

Overall, nearly seven out of 10 Americans (68%) were able to identify without any prompting from the interviewers that the "three" in John 3:16 refers to the chapter where the biblical reference is found. More than three out of ten adults either gave an incorrect answer (15%) or ventured no guess (17%).

Among Mr. Tebow's generational peers--Americans who are 18 to 27-year-olds--the basic understanding was even lower than the national average (61%).

Practicing Protestant Christians (80%) were more likely than were practicing Catholics (66%) to understand the reference. One of the surprises: a majority of people outside Christianity (59%), including those affiliated with another faith or atheists and agnostics, said they understood the "three" refers to the chapter.

In comparison with other things Americans know about the Bible, awareness of the chapter reference was comparatively strong. Slightly more Americans were able to identify correctly the first book in the Bible as Genesis (76%). But fewer were able to name the original languages of the Old Testament (Hebrew, named by 57%) or New Testament (Greek, by 27%).

David Kinnaman, president of Barna Group, directed the study on behalf of the American Bible Society. He put the findings in context: "The controversy surrounding Mr. Tebow ends up affecting so many people because--whether they have an affinity for sports or not--most Americans have at least some knowledge of the Bible and connection to Christianity. Despite the pundits' protestations, more Americans than one would expect know exactly what Tim is Tebow-ing about in the end zone."