Why Is the Main Affidavit in America the Bible?

Affidavits have always been a part of the law, courts and justice. However many people find it uncanny that in the United States, it is the Bible. The affidavit is mainly a written text which the witness swears on that what they say is the TRUTH.
Why the Bible? Christianity may be the main religion in the United States but a fair amount of Americans are not Christian or would question just how realistic it is.…