Quick Christening card question

[SignoraStronza]

Wonder if anyone could advise. We've been invited to the christening of my friend's baby and I'd like to order a personalised keepsake card.
Would I use all of the names i.e. John Henry Smith, or just the first and middle names?
Am not religious at all any more and we don't get invited to many, but this is an important day for our lovely friends and Is like to get it right!
Thanks ever so much.