(I posted this same question in the liturgy forum but think it fits better here in the apologetics forum. Sorry for any confusion by posting twice.)
I know that one must attend Mass on Sunday if possible. However, I have always been told that after attending Mass you may attend another service, for example, a protestant one. There are various reasons to do so: invited by a friend, have non-Catholic familiy members, etc.
Last night at our church discussion group we discussed # 206 from the Baltimore Catechism #3:
Why does a Catholic sin against faith by taking part in non-Catholic worship?
A Catholic sins against faith by taking part in non-CAtholic worship because he thus professes belief in a religion he knows is false.
There is a more indepth answer to this question and the proceeding one which asks “How does a Catholic sin against faith?”
The problem at the meeting arose when a convert couple discussed how their son is very active in an evangelical church and how some times the mother goes to suppport the son who is a youth pastor. She was having a tough time seeing her presence at his services as a sin.
FYI, these are normal services she attends, not special occations like funerals or weddings.
What concrete sources can I refer her to that may explain further this teaching? I don’t want to turn her off or scandalize her but want her to be able to understand and embrace it.
Thank you in advance for your time and help. God bless you!