I converted to Islam from Christianity and up to now I have been reluctant to change my name to a Muslim one. Is it neccesary according to Islamic doctrine?

All perfect praise be to Allaah, The Lord of the Worlds.  I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

There is no problem if you retain the use of your old name unless it is among the prohibited names such as "Abdul-Maseeh", which means the slave of the Messiah, "'Abdul-Rasool", the slave of the Prophet, or the like, from the polytheistic names that should be changed.

If a name contains the meaning of laudation or indicates a bad meaning, then it is preferable to change it. The Prophet Muhammad , changed some names of his companions in this regard, such as his changing the name of Hazn (rugged and hard ground) to Sahl (ease) and Barrah (pious) to Juwayriyah (a blessing of Allaah).

 It is not compulsory for a person who converts to Islam to change his father's name or the names of his forefathers, because 'Abd Al-Muttalib, which means the slave of Muttalib, was a paternal forefather of the Prophet while 'Abd 'Uzzah, which means the slave of the idol 'Uzzah, was a maternal forefather of his, and he did not change these names.

Allaah Knows best.