The practice of choosing a baptismal name goes back many centuries and is still recommended today universally. Lesser known is that one may choose yet another name at the occasion of every sacrament that confers an indelible mark on the soul, namely baptism, confirmation, diaconate ordination, priestly ordination, episcopal ordination as well as papal election. Also, one may choose a name when making religious vows or solemn promise of virginity.
The name chosen may be taken from two sources:
1. The name of a known saint of the Catholic Church, canonized or otherwise (since not all accepted saints have been canonized) or the name of a virtuous biblical person, or variations of their names. The idea here is to adopt a patron saint that is particularly inspiring to the person that he or she may better follow Christ by befriending and imitating the patron saint.
2. The name of a virtue or Godly gift, like Patience, Faith, Grace, Joy, etc. Again, the idea is to inspire the person to strive for holiness by growing in particular virtues.
Otherwise, why do we call it a “Christian” name?