I believe my elderly uncle is a non believer. There have been signs. He has not attended church since my grandma died in 1996 - except for funerals. Refuses to lead prayers at family gatherings, although, he will mumble along eyes open with the rest. Did not pray at my dad's (his brother's) funeral last summer. Avoids religious conversation and changes the subject when it comes up. Never gives a reason why he doesn't go to church even with his long time girlfriend.
My dh thinks my uncle is an atheist. I have asked my cousins and they think he is a backsliding believer. I tend to agree he's at least a doubter. I talk to him more than any of them. How do I talk to him about his lack of faith? How do I assure him it's okay, I don't believe either? I don't know how to talk to him about this or even if I should. He seems to be okay with being religiously ambiguous. Maybe I should just leave well enough alone. He's an old man. He's obviously happy with his life and being cagey about his faith.
He is your uncle, you know him better than us strangers, so it ultimately should be up to you to decide.
My guess is since you are saying he is old and happy, then why bringing up such a serious subject with an elderly person?)) Maybe you need this conversation more than your uncle does?
P.S. I didn't realize you really still have 'family prayers'! I mean, saw it in the movies but from there it still looked fictional. I've never taken part or seen a family prayer! Thank god for that! hehe ;) )))))
Why do you want to talk to him about it? Are you concerned about his welfare? Do you think he might be lonely?
You could simply start talking about your own discomfort with family religious events because you are an unbeliever, an atheist and see how he reacts but you are probably taking a chance if you have not outed yourself already.