I baptise thee...

Came across that old idea on the net the other day that "you can't change your Christian name".  Now I think I've mentioned before that, under English common law, you can call yourself whatever you want provided that by so doing you are not breaking the law or seeking to do so.  So how can you reconcile those two statements?  Well, the answer is in the wording.  Your Christian name is the name you were given at your christening, or baptism, and as a christening is a one-off event, it follows that the name you were given then you are stuck with as your Christian name for life. Well, that's not entirely the end of the story.  At your christening, your godparents make certain promises on your behalf.  When you become of sufficient age, Christian dogma allows for a ceremony called confirmation whereby you confirm those promises on your own behalf.  Now there is a theory - don't know if anyone's ever done it - that at confirmation you can if you wish revoke the name you were given and choose another one.  But the point is that you need to differentiate between your first name - that is the name by which you are known to officialdom, and your Christian name (if indeed you have one) - the name by which you are known to the Church.  The former can be changed whereas the latter (subject to what is said above) can't be.