My DS is being christened in a few months, and my sister is one of his Godmothers. Her husband is refusing to come to the christening as apparently he "doesn't believe in it". He and my sister got married in church 7 years ago, and attended church weddings (inc mine) so this is a recent thing. I don't mind if he doesn't join in the vows about prayer etc just as I wouldn't if I attended a wedding of another faith, but I'd still go.
He's entitled to his views but I find it odd that he's not coming to his nephew's christening, especially when his wife has an important role. They v sadly don't have children, which may be part of the reason for his non attendance, but my sister will find it far harder to deal with all the "when will you have kids?" prying questions on her own, I'd be seriously unimpressed if my DH did this to me!
He also didn't attend my DD christening 2 yrs ago, apparently he had a cold. Bit annoyed then as it was a sit down meal and we'd already paid for it / had seating plan etc.