Appropriate attire for a man at a christening

[JosieRosie]

Not sure if this is the best place to post this but hey....

DP and I have been invited to a christening and it's our first It will be in a Catholic church on a Sunday pm in a few weeks time, with an informal reception in a church hall straight afterwards.

Neither of us know what would be appropriate for DP to wear? Does it need to be suit and tie? Suit and shirt? Trews and shirt?
All advice gratefully received - thanks!

Smart trousers and a shirt I would say, tie optional. Some men wear suits but by no means all.
The only thing I would steer clear of is anything too casual like sportswear/trainers etc.
Have a lovely time

Cheers luv! x