I have seen many posts on this issue, but most seem to have some kind of presupposition of foul play.
1. You are attending for the sake of a friend or loved one.
2. You are not looking for truth outside of the Catholic Church.
3. You do not receive protestant "communion".
4. There are no ulterior motives from your friend or loved one to convert you.
5. This is not replacing Mass.
Can a Catholic attend non-catholic services such as worship, choir concerts, plays etc. in good conscience?