I said, "Eh al-Kalam dah?" (What is he talking about?) So I tried to explain how that is my Islamic name. He responded, "Ghalat" (you're mistaken). He then went on to give two reasons why I should have not changed my name and why I should return to John:
1) Islam teaches the utmost respect and honor for ones parents—Muslim or not. This is clear in the many verses of the Qur'an that command us to do so, and some of them specify that the only exception is in obeying a parent's call to an evil lifestyle. Changing your name not only erases and invalidates their very first interaction with you as parents, but gives the idea of you splitting from your family, which can be perceived as breaking the ties of the womb.
2) As long as your original name's meaning isn't contrary to Islam, then it would be in the best interest of promoting our faith (da`wah). When people see that Matt, Dave, Robert, Sarah, Lisa, Emily, etc., are Muslims whose language and general customs are similar to them it takes away that "Islam is a foreign religion" vibe we often give off. This is in light of the hadith (record of the words or actions of the Prophet Muhammad (PBUH): "Facilitate things for people and don't make things difficult for them. Give glad tidings and don't alienate people" (Bukhari 69).
Of course, for someone who has been known to many people by a name for some time, it would be a hassle to change it back. The fact is that, as the sheikh said, my mother was indeed somewhat offended and told me that "my brothers" can call me what they want, but that she will always call me John.
It is no one's business what a person chooses to be called as long as it carries a good meaning. The advice here is that it is not part of the sunnah (prophetic tradition) to change someone's name as a result of their embracing Islam. If someone of their own accord wishes to change their name, then that is their right, but don't encourage it, as the benefits are there for them to keep it.
And God knows best!