Ezekiel provides some details concerning the fall of Satan. The statement in verse 15 is the closest the Bible ever comes to spelling out the origin of sin: unrighteousness was found [in Satan]. Somehow, a perfect and holy being was found with unrighteousness.

And what this unrighteousness consisted of is given in verse 16: you have sinned. How did he sin? He sinned by the abundance of your traffic.

This Hebrew expression means, “to go about from person to person or from place to place.” The picture is that when unrighteousness was found in Satan, he went from angel to angel trying to secure their allegiance by slandering God. One-third of the innumerable number of angels were convinced by Satan and joined him, but two-thirds did not. The specific sin here was the act of slandering God from angel to angel. This act of sin originated from the sin of pride; then the sin of slandering God led to violence; Satan caused violence in Heaven by leading a revolt.

Satan To Eve Surly You Must Not Die...