I am a Protestant ; I attend Mass because since I have a lot of Catholic friends / colleagues and so on (probably more than Protestant ones due to the “religious landscape” in France ) and when they invite me I go … and I sometimes go on my own… there are things I agree with in the Catholic Church, contrary to what you said about “Protestants” in general I don’t "protest against it " ;
I don’t believe in the Real Presence, but during the Eucharist Catholics also remember Christ’s atoning death for us, so even if I don’t take part in it ( because it is forbidden by the Catholic Church, and if I am in somebody’s house I find it normal to respect his rules )–I mean I don’t take the host–, I ask God to forgive my sins, I thank him for his Son’s sacrifice, and since I know that is what Catholics also do, DESPITE THE DIFFERENCE ( Real Presence or not ) I feel in fellowship with all the Catholics who are in the communion line because I know that they are also remembering Christ’s death…
I don’t say the “Hail Mary”, nor do I use the sign of the Cross, I just keep quiet and nobody ever jumped at me for that ; but when the Catholics say the Lord’s prayer I say it with them, when they pray and if I agree with what they pray for ( which is very often the case, except when they pray for the dead, then I don’t associate myself with these prayers ) I fully associate my prayers to theirs, I use the “response” ( I don’t know what you call it, sometimes it is simply amen but sometimes there is a kind of chanted response, like Lord we beseech you …) they use ; there are some Bible readings during Mass, three if I’m not mistaken, then just before I ask God to open my heart; if I agree with the hymns I also sing them, anyway there are hymns that are sung by both Protestants and Catholics, and even when there are specifically Catholic hymns and I agree with the words, I also sing them ( well, if I can catch up … if it is too difficult I don’t sing but I say the words in my heart, silently …)
And then I also listen to what the priest preaches, sometimes I agree with him, or partially, but I wouldn’t agree with everything a “Liberal” Protestant minister would say either, so I don’t really see the difference …
The French Protestant Federation has a Bible reading guide that proposes texts for everyday , with a small comment ; recently, they have decided to add some texts on Sundays and “special occasions” ( I mean Christmas, Easter … I don’t know the exact English word for these days … festivals ??? holy days ? ) and the texts they “add” ( they propose to read after the usual two texts a day ) are the texts of the Catholic Church for that day …
And when, on Sundays, or at Easter, or at Christmas, I read these “extra” texts, I’m happy to know that Catholics who attend Mass on that day will hear the texts I’m reading, I also feel in fellowship with them thinking we are reading or hearing the same texts on the same day ( there is just one exception : if among the texts proposed by the Catholic church some are taken from the Deuterocanonical books, then they are not “proposed” by the French Protestant Federation, but I wouldn’t be shocked if one day they went further and proposed them too --maybe giving the references in a different colour for instance to underline they’re Deuterocanonical …we use a lot of different Bible translations, not only Protestant ones, because some French Catholic translations are considered very good even by Protestants, so we sometimes also read the Deuterocanonical books : we don’t give them the same “authority” as to the other books, but it is not “forbidden” to read them )
Well you see there are a lot of things a Protestant can do in a Catholic Church …
I don’t see any problem going back to my own church “after that” ; I don’t feel I’m sinning attending Mass ( since I don’t do anything I disagree with there …) from time to time, even my minister does so …
But I don’t go to Mass regularly, sometimes I don’t go for months, because sure I prefer to go to my own church …
Well well well I hope I haven’t shocked anybody here ( Catholic or Protestant )…
Some Catholics also come and “visit” us …
I don’t want to “minimize” the differences there are between us ( I don’t even agree with infant baptism, I’m Evangelical ), but I try to do as much as I can with Catholics IN SPITE of the differences …
There are types of Masses I couldn’t attend because I think I wouldn’t feel at ease at all, for example some Catholics invited me to “Eucharist Adoration” ( I don’t know if that is the exact term in English ) , well there I would surely feel very ill at ease since I don’t believe in the Real Presence ; or I couldn’t attend a Mass said for a dead person …
A lot of French Protestants are so occupied trying to get nearer to Catholics that they forget … the other Protestants : I’ve never attended a Reformed or a Lutheran service