During the Roman Republic, Roman males were often referred to by four names. Examples of this is Gaius Julius Caesar Imperator. The first name (Gaius) was the persons “given” name called the “praenomen.” The second name (Julius) is called the “nomen” and it is the tribal name, so Julius Caesar’s real first name was Gaius and he was from the Julian tribe. The third name (Caesar) is called the “cognomen” and it was the family name, so in his case, Gaius was from the Caesar family.
Everybody knows or has at least heard of Julius Caesar because he was very famous. Because of this, his family name (Caesar) became a tribal name and a recognized Roman tribe. One of his relatives was a man called Gaius Caesar Augustus Germanicus, who led his legions to victory in eastern Europe and the Rhine River, or Germany. His son was called Gaius Caesar Augustus and was called “Little Boots” by the soldiers because he used to dress as a Roman soldier when he was with his father in Germany. The nickname “Little Boots” in Latin is “Caligula.” So, his name was Gaius Caesar Augustus Caligula.
Now, let’s look at the Apostle Paul. Paul was Jewish and his family were Roman citizens. His given name (praenomen) was Saulus (Shaul in Hebrew). His tribal name (nomen) was from the Jewish tribe of Benjamin. His family name (cognomen) was taken from the town where he was born, called Tarsus.
Now, a fourth name could be added because of some honor or title they have received, like a nickname. This is called the “agnomen” and given to someone for some special reason. Not all Romans had a fourth name, but it wasn’t uncommon. As we have mentioned before, Julius Caesar had four names, Gaius Julius Caesar Imperator. The term “imperator” means an absolute supreme ruler and certainly applied to Caesar because of all his military victories. So his full name was Gaius Julius Caesar Imperator. Saulus also had a “agnomen” called “Paulus.” It means “small” or “humble” in Latin and it is not clear who gave him this name, possibly a Roman official.
So, Paul’s full Roman name was Saulus Benjaminus Tarsus Paulus. There are some who think that the name “Paul” was given to him after he became a “Christian” which signified his break from Judaism, but that is not true. Paul had this name before that and remained Torah observant and a Pharisee according to custom and education, remaining true to his calling (Acts 23.6; 1 Cor 7.17-20). Saulus was also his name (Acts 13.9) and he went by both names.
Yeshua always called him Saul (Acts 9.4). Ananias called him Saul (Acts 9.17) and the Holy Spirit called him Saul (Acts 13.2) after he believed that Yeshua was the Messiah. God never changed his name to Paul and there are no Scriptures to prove that. He just “dusted off” his Roman name because he was sent to the Gentiles on his missionary journeys and it was a name they were accustomed to. There is no spiritual significance to using Paul over Saul. So, in the Roman world, he was known as Saulus Benjaminus Tarsus Paulus.