Ethics concerns the system or code by which attitudes or actions are determined to be right or wrong. Only two sources can serve as the basis for ethical conduct: ethical conduct is either regulated by God or man.
If ethics derive from God, then he, based upon his nature and out of his
sovereignty, determines what is right and wrong, and to that standard man submits. This is the biblical position.
On the other hand, if ethics originate strictly with man, then each human being is
autonomous, crafting his own moral code and living as he chooses. Logically, he must only avoid such consequential penalties as society may impose.
The idea that every person determines their own moral code is a fallacious system of thought. No one can live by it ultimately. Every rational person will eventually draw a line with the declaration: "This outrageous social abuse (e.g., murder, rape, etc.) is wrong!"
However, apart from the concept of God and a divine revelation containing ethical guidelines, there is no consistent defense of a reasonable standard of human behavior.
Jesus Christ is the noblest example of ethical conduct that man has ever witnessed.