Some time ago I stumbled upon an interesting definition of the Eucharist. The definition — that was given by a low church evangelical whom I have decided not to reveal — was that the Eucharist was “the Gospel to the body.” I’m pretty sure that I and the mentioned person would differ on what that would mean (or what the Eucharist is) but I want to adopt that definition as my own. But this definition begs a question: what is the Gospel? I will not give a definite — or pehaps even good — answer to that quesition here. I’ll just offer my 2 cents worth of thoughts on the subject.
The first verse in St. Paul’s first epistle (judging from the Canon) we read that the Blessed Apostle refers to himself as “the servant (gr. δοῦλος) of Jesus Christ, called as an apostle, set apart for the Gospel of God.” For St. Paul the Gospel was the most important part of his ministry. But was was the Gospel? Oftentimes — and this might be because of the idea that ‘the medium is the message’ — it seems to me that people regard the Gospel as just the Scriptures or the message. But this seems wrong, too narrow. Let’s say that I win the lottery, and call a friend, and say, “I have good news; I won the lottery.” The goodness, then, doesn’t refer to the fact that I have news, or to the form of the news themselves, but the content of the news; the winning of the lottery. The same, I think, goes for the Gospel. Which, in its greek form (εὐαγγέλιον), literally means ‘good news.’
And what is the content of the Gospel? The core content is this: Jesus Christ, the Word made flesh. Further on, the Gospel tells us that we must participate in Christ. This, above all, is the core message of St. Paul. To me it seems then, given the definition of the Eucharist as “the Gospel to the body” and given that one holds to the real presence, that it follows that the Gospel is more then just the ‘story’ of Christ and of his deeds: it is the very reality. “The Gospel for the body” would then be: “The true content of the Gospel for the body.” And the Gospel tells us how we are saved: by the blood of Christ. And this, Christ tells us (Matt 26,28), is given to us in the Eucharist.
Could this be a fruitful way of putting it? With this in mind, read St. Paul’s words in Rom 15,15b-16 (in my translation):
[I’m given a grace by God] to be a liturgist of Christ Jesus to the Gentiles and to be a sacrificial priest with the Gospel so that the Gentiles may become an acceptable offereing, sanctified by the Holy Spirit.
 This is my own translation, built on the language structure of the RSV-CE. See here.
 To read more on this theme of participation I recommend Taylor Marshall’s blog on the Catholicity of St. Paul.