There are millions of people who profess no religion nor any belief in a god. They are atheists. Others, agnostics, believe that God is unknown and probably unknowable. However, that obviously does not mean that they are people without principles or ethics, any more than professing a religion means that one does have them.
However, if one accepts religion as being “devotion to some principle; strict fidelity or faithfulness; conscientiousness; pious affection or attachment,” then most people, including atheists and agnostics, do have some form of religious devotion in their lives.—The Shorter Oxford English Dictionary.
To answer that, you we need to know something about the background of the world’s religions.And that is all in the Bible. (1 John 4:20, 21)