the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
It is preferable for a Muslim to give his child a name that has a good meaning and expresses that child’s Islamic identity. However, it is not unlawful to give a child a non-Arabic name. Many Muslims give their children Persian or Turkish names and there is nothing wrong with this. It is forbidden, however, to give a child a name with the express intention of imitating or identifying with the unbelievers.
A person who accepts Islam is under no obligation to change his name unless his name conveys a bad meaning. If his name conveys a bad meaning, he should change it even if it is an Arabic name. The Prophet (peace be upon him) changed the names of some of his Companions who had bad names, even though those names were in Arabic. In the early centuries of Islam, non-Arabs who entered Islam were not requested to change their names unless their names had bad meanings. The practice of converts changing their names is a custom that developed much later.
Any name which conveys any specific religious meaning for any religion besides Islam must be changed to any other normal and reasonable name. Therefore, the name Christina should be changed.
Otherwise, a new Muslim may change his name only if he wishes to. We must point out that he may only change his given name. It is unlawful for him to change his family name. Changing the family name is a mistake many new Muslims make.
In Islam, the Middle name is generally the first name of the child’s father and it indicates the child’s parentage. It would be best to change one's middle name to one's father's first name if it is not that already.
Source: Islam Today