This isn’t quite as easily answered as one might expect, as it depends upon the situation and your relation to the child being christened. If, for instance, they are a niece, nephew, cousin or younger sibling, then no matter what the situation is, it would be best if you could get them something for the occasion. If your relationship to the child is quite far removed, then it might not be necessary, but in that situation it comes down to the cultural importance of the occasion. A lot of people christen their children because they were and because it’s part of what parents do, in which case it may not be necessary. However, if you’re in a religious community where you have a strong interrelationship with everybody within it, then contributing to the festivities through a gift is a way to show respect and build a relationship with a new member in the community.