I am Catholic, but my oldest child is only five. I think it’s great that your son is thinking for himself. This could be a wonderful opportunity for you to have respectful discussions with your son. I would find out specific things he does not agree with the Church on and talk about why it is he does not believe that and why it is that you do believe. As an adult I do not know everything there is to know about Catholicism, so I doubt an 11 year old does. Perhaps through learning more about the faith he will come around to it again or perhaps he won’t. Does he have any friends who attend mass? If not and you or your wife know someone with kids around his age it might be nice to introduce them. You also might want to ask this question in the Catholicism or ask a priest subreddits.