I'm an ex-catholic atheist from a religious family (including two vicars) and I find the idea of a christening as just a social occasion really odd and slightly abhorrent. Especially if the parents have chosen not to get married in church because they aren't religious and yet opt to have a christening because while the marriage ceremony is mostly about making vows to each other, christenings/ baptisms are about making some pretty strong vows to god. It's a much more religious ceremony, not surprising as it's about joining the faith.
Standard CoE wedding vows:
N, will you take N to be your wife/husband?
Will you love him/her, comfort him/her, honour and protect him/her, and, forsaking all others, be faithful to her/him as long as you both shall live?
Standard CoE christening vows:
Do you reject the devil and all rebellion against God?
I reject them.
Do you renounce the deceit and corruption of evil?
I renounce them.
Do you repent of the sins that separate us from God and neighbour?
I repent of them.
Do you turn to Christ as Saviour?
I turn to Christ.
Do you submit to Christ as Lord?
I submit to Christ.
Do you come to Christ, the way, the truth and the life?
I come to Christ.
Effectively the parents/godparents are lying to all the above aren't they? Well except no 2 I guess (although personally I'm a bit uncomfortable with the concept of 'evil')