The respected Gallup organization has been polling America on thousands of topics for decades. In the area of religion, polls show that Americans by and large define themselves as religious people, and the majority identify themselves as Christian.
But polls also show that people (including those who consider themselves Christian) are amazingly ignorant of the Bible, unfamiliar with its most important people and teachings.
This contrast has been apparent in the polls for decades. Yes, Americans are (or claim to be) religious. No, they do not know much about the Bible.