Is it an ethnic Catholic wedding? I'd willingly sneak into an Irish wedding. Italian weddings are a hoot too, not to mention Polish weddings. Don't worry about your feet catching on fire, that's what the holy water is for. Congratulations and good luck to your sister. B-)

Asbestos I can tell you're out of luck with your footwear. But I wish you all a very happy future ?

Order Eaters

I understand not wanting to go to a church wedding, especially a Catholic wedding (they can be so long!). But, it is what it is. Go, support her, as you would want her to support you in your life decisions.

And I think Dr. Scholl's makes an atheist insole for such an occasion...

Probably best to enjoy the day. One doesn't just catch religion like the 'flu. You and your sister will have a great time. The following day you will carry on the same ideology you had as you entered the church

Enjoy the experience. regarding the shoes, standard unicorn skin ones are always effective.
On a more serious point, i was asked to be a god parent to a baby many years ago, and declined, as i took the view i would be promising to ensure she would grow up a good Christian. for 18 years i have been forced to introduce her as our ungod daughter.

Just do it and enjoy it, mate. It’s your sister and she’s getting married. There’s a lot of meaning I’m it already without invoking god(s)

Ice bags round your feet should help ? It will almost be like walking on water, that should appease them ?

This might have been in jest but my opinion and advice would be to get over yourself. It's her day, you won't melt - it's not a big deal. OMG you have to attend a Catholic wedding - life is over as we know it - it's complete BS. If you weren't a self centered person your thoughts would not be on the ceremony or rituals but on how happy and radiant your sister is on HER day.