It has been in practice for some time now that when someone believes the gospel, during water baptism, his name will be changed or another name will be added to his name. When this practice is questioned, people seem to give examples like Paul and Abraham. Truly God changed the name of Abraham but he did that to enhance the faith of Abraham as regards the promises he made to him. Hence, the name Abram which means “the exalted father” was changed to Abraham which means “the father of many nations” and that was what God promised him. Similar condition holds for Sarah. The case of Paul is different from Abraham’s; Paul who was a Jew has a Jewish or Hebrew name which is Saul and a Greek name which is Paul. Both names do not mean the same thing but they have always been his name even before his conversion. You would notice he was called Saul in Acts 8.
As for Saul, he made havoc of the church, entering into every house, and haling men and women committed them to prison.
As a matter of fact, after he has been saved, he was addressed as Saul not Paul, first by Jesus and then by Ananias. (Acts 9)
He probably decided to pick his Greek name because of acceptability since he was sent as a minister to the gentiles, and the gentiles were under the Roman Empire. Greek was their official language in the Roman Empire then. Hence, one can say it was part of Paul’s strategies to invade the Roman Empire with his ministry and the gospel of our lord Jesus Christ. Paul would later testify about himself when he said he became all things to all men that he might win some.
1 Corinthians 9:22
To the weak became I weak, that I might gain the weak; I am made all things to all men that I might by all means save some.
Notice, he said he did those things so that he would by all means save some. Hence, picking his Greek name in order to invade the Roman Empire was probably one of the ways he chose to get the attention of gentiles in the Roman Empire.
It is noteworthy; that Paul claimed to be both a Jew and a Roman and that should explain why he would be given both a Jewish name and a Greek name (Acts 16:37 and Philippians 3:5).
Hence, there is no such practice or doctrine that prescribes the change of name after one has believed the gospel. One can change their name anytime they want to, it means doing it doesn’t make you right and not doing it doesn’t make you wrong. There is room for allowing entirely personal reasons to play as touching the changing of one’s name but it is not a practice one should attach spiritual relevance to.
Another reason people give is when it comes to names associated with idols. Just like Paul said in his letter to the Corinthians, we know that an idol is nothing and that there is only one God (1 Corinthians 8:4). But for conscience sake, if anyone judges that he is not convenient with such name and he thinks it is best for him to change his name then let him do so. But for people that know that the new creation is not after the natural, that name is a natural way of identification and that it doesn’t have the ability to change one’s fortune for bad or good, if they have decided to retain their name they have done nothing wrong. When God created the first man, he didn’t give him a specific name other than man and that was because there was only one man. Although name can affect one psychologically, which is why there is room for anyone to call themselves what they like, however, it is best not to regard names more than a natural means of identification. This is especially because of the mental security one needs so that one won’t be affected negatively when one is called by a name that might appear or sound like something that one is not convenient with. Hence, people can change their names if they want for it is best that they bear a name that inspires them unto greatness but such practice has nothing to do with Christianity.