Re: What should we do…
This for some reason reminds of one of the signs of qiyamat that mosques will be decorated but hearts will be empty. From the examples that you stated such as giving charity and paying for a mosque, it is evident that it did have an effect on the kids because your nephew is not materialistic and is down to earth. He maybe agnostic but treating people with respect and still partaking in religious rituals such as fasting and eid is all the result of his upbringing. One can *try *their best to lead by example but nothing is guaranteed in life and the rest is up to God… he guides who he wills. I would also like to point out that I live in the same “here” ie. western society and have seen plenty of hard core christian families shunning their kids for not following their religion or marrying someone of another faith or ethnicity. There are a handful of reverts in our community whose families do not want anything to do with them.
If you want to go that route then it can be argued that sugar is a drug too since it affects the release of certain hormones in the brain. From what I know, there is a hadith that if anything in access is intoxicating then even a little bit is prohibited so those who are smoking weed but consider themselves religious are once again an example of picking and choosing. Also, I am curious what is your definition of a religious person?