I think I understand what you’re saying - that if I read the Formula of Concord, I scratch my head and wonder “why exactly we’re we being so grumpy about the Catholics?”
As I’ve heard it explained to me is that we’re looking through modern eyes where we view Transubstantiation as a affirmation of the Real Presence, and were in the Mass is a re-presentation of the once and final sacrifice of our Lord. I think we also ascribed some of abuses of the Eucharist (for example, spiriting away hosts for personal use) as springing from Eucharistic adoration.
I’ve been told that the general Lutheran understanding of the Catholic position was that Transubstantiation was perhaps an alternative to the understanding of the Real Presence, and where it was felt that the priests were claiming a more extensive role in the Sacrifice of the Mass.
So while I think there’s much to work out between out two communions, our complaints about Catholic understanding and practice need to understood in the context of the times, and hence are not so strident as they seem.
Perhaps the reason you are scratching your head is that you are not of the same mind as the Formula of Concord.
It is impossible to say that the Formula of Concord, while not relevant today, is relevant and correct in the context of the times of its composition. For one thing, it is very relevant today, because it is foundational to Lutheran belief and teaching in the present day. It remains a confessional document for the major American Lutheran bodies. More importantly, the truth of the sort of statements it makes is not dependent on historical context. When the Lutherans say, “[by these words], the papistical transubstantiation may be rejected and the sacramental union of the unchanged essence of the bread and of the body of Christ indicated,” they mean exactly what they say. The “essence” of the bread remains unchanged in the sacrament. There is no doubt about the meaning of their words. They clearly explain the terms “substance,” “accident” and so on early on in the Formula of Concord and indicate that they are using them according to the universal understanding of these terms and even say that they are necessary to explain correct doctrine. As far as the FC is concerned, it does not even really matter what these “papists” taught. They are firmly rejecting (“with heart and mouth”) one position they clearly define in the FC (that the substance of bread is changed into the substance of Christ’s body), and proposing another definition (that the substance of the bread remains unchanged in the sacrament) for belief by all the faithful. This doesn’t really fit your narrative that the Catholic view is not false and erroneous according to the teaching of the FC, which explicitly states that the Catholic view is “false, erroneous, and misleading.”
You cite an alleged practice of people stealing hosts to keep as talismans. What evidence do you have for this being a widespread practice, much less one condoned by the Church? Old Protestant polemics? You heard it in a Lutheran sermon somewhere? If this allegation is going to be meaningful evidence for discussion, you will have to cite firm evidence. Now of course, if someone without authorization steals away the sacrament in their pocket, they are violating the law of the Church and treating the Sacrament with gross irreverence, but that does not justify denying, as the FC did, that Christ remains truly present in such a situation or denying transubstantiation. But there are many cases when it is good to reserve the Sacrament outside of the mass. Many churches now have “perpetual adoration” chapels where the Sacrament is reserved for public adoration around the clock. The pastor of our parish has a private chapel in the rectory (located a good drive from the church grounds) where the sacrament is reserved for adoration outside of the mass. Catholics, many times laymen, also take the sacrament from the Church to visit the sick so that they may receive the sacrament, and there is no requirement imposed that there must be an abbreviated service (the official directives of the LCMS) as if to re-consecrate or, even worse, to simulate re-consecration of the host, since Catholics believe that the real presence remains as long as the sacramental species remains.
Again, if you are scratching your head about the “grumpiness” on the part of the FC toward Catholics, it is likely because you do not agree with the Formula of Concord. Do you believe that
(1) In the Blessed Sacrament, the substance of the bread remains unchanged?
(2) That Christ is not present in the Sacrament during Eucharistic processions or when the Sacrament is reserved in the tabernacle?