As an interesting aside, JG Machen would have attended RC services but would not have partook of the Mass. The problem is that it does not in my opinion bear good testimony to Christ to attend a service of worship which is explicitly against His glory; the Lord has told us to "flee from idolatry". Having said that, I do respect the motives of others on the board and don't think that they are intentionally trying to harm people.
Just to let you know my understanding about it a little more Daniel..... Have you ever had a friend at a Pub who needed your help because he was so blasted blind to his situation. I don't go to pubs or bars much. It isn't because I don't like to drink. I just don't think they are good environments that promote a good lifestyle. In fact I like my drinks overly strong. But I would go to a bar to be with a friend to help him get home. And I don't like bars and pubs either.
Something that is missing in this world is friendship. True friendship. And I can be friends with a Catholic. Some Protestants might have problems with this depending on the local environment.
This is one of my favorite Passages in the scripture.
(Rom 5:5) And hope maketh not ashamed; because the love of God is shed abroad in our hearts by the Holy Ghost which is given unto us.
(Rom 5:6) For when we were yet without strength, in due time Christ died for the ungodly.
(Rom 5:7) For scarcely for a righteous man will one die: yet peradventure for a good man some would even dare to die.
(Rom 5:8) But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us.