I have been trying to research the history of the Lutheran liturgy, Divine Service, but I have not been able to find out too much other than it being based on the Pre-Tridentine Mass. I have participated in Mass at an ELCA, LCMS, and RCC and they are all strikingly similar. I understand that some of the prayers of the Pastor are different between the services, but is it merely a coincidence that the Nuvos Ordo Mass is so similar to the Lutheran Divine Service?
Catholics in our Lutheran congregation have several (at least 3-4, maybe 5) told me the services are 'the same' or even 'identical', meaning to the local Catholic churches they also have attended. Myself having attended I think now 3 masses at local Catholic churches (if you count 1 instance of a confirmation mass), I agree that basically one could imagine one was in either church, with not much obvious difference. (I think I've attended in person 6 or 7 Catholic masses altogether in my life, but it's hard to keep track of how many I also watched through video.)
Not only is the liturgy the same as far as I can see, but also they are the same in tone and spirit usually also.
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I'd like to offer more of my view of these churches from a very neutral viewpoint. I did not grow up in either church, but have gotten to know a lot about both.
We remember the reformers were aiming to reform the Catholic Church, keeping most everything, and only putting aside the things not in accord with scripture in the reformers view that had crept in, such as the purchase of indulgences, infamously.
To reduce to the most key thing, it's like Martin Luther was saying (to simplify) in effect: Don't forget Ephesians 2:8-9.
(Note today the key part of this is resolved -- the Catholic church emphasizes that salvation is through grace from God as best I understand in their catechism. Lutherans aren't as a rule all ignoring Ephesians 2:10 either -- many don't ignore this verse. See? There is even a formal agreement on justification. So, today, it's just tradition to even be separate in my view, but also this isn't of great urgency either. Rather love is the crucial thing always.)
I'd like to also say that in my view now, after reading carefully some sections in the RCC catechism, that I think there are no potent and truly meaningful differences between the Lutheran and Catholic churches that I can find (remembering both large churches will have plenty of individuals doing whatever individual errors, of course). I do accept that those in Christ passed on could indeed be asked to pray for us, though I myself haven't yet felt I needed to, and can also find believers here alive in person I can ask if needed. There will always partisan people that will sometimes use sophisticated language to try to justify their judgements (but they do this not only against other denominations notice, but also against their own, tellingly). I'm never imagining that most people in any one church all agree about everything either! I mean it's as easy to pick out differences inside either church as compared to differences between them. I consider such efforts to emphasizes differences to be mostly just a work of man and not of God, but also, I don't think it's crucial to formally blend the churches. Rather, it's crucial to obey Christ and "love one another" as He commanded.
The people will blend, in brotherhood, if they are believers.
It doesn't even matter what a theologian writes in comparison to that.