It’s true that you didn’t say—in the sense that you didn’t say word-for-word—that our hearts are our spirits. But unless you want to distinguish between “our hearts are our spirits” and “our spirits are our hearts,” you did IN EFFECT say this. Inserting the word “spiritual” into your statement doesn’t change that. (But this is a minor clarification.)
Now, I understand that you did not mean that literally, but that you meant it by way of “example” (although I’m pretty sure that’s not the word you really meant). Similarly, I also understand that what you said about the Spirit being the heart of God was also by way of “example.” That is not the ground of my objection.
I agree with you that there are differences between the Persons of the Godhead. To take the easiest—and most timely—example, neither the Father nor the Spirit was crucified. To take another easy but often overlooked example, not all of the commonly so-called spiritual gifts are gifts of the Holy Spirit. SOME are gifts of the Spirit, others are gifts of the Son, and others yet are gifts of the Father. Or we can take an extremely important historical example: the question of whether the Holy Spirit “proceeds “from the Father only or from both the Father and the Son split the Eastern and Western churches. (How sad that today many Protestants aren’t even aware of this issue, don’t understand it, or don’t think it’s important.)
BUT we need to be very careful in addressing those differences. In particular, 2 issues are important. 1) these differences cannot (if one wants to be an orthodox (lower case “o”) Christian), be seen as differences in substance, essence or nature between the three Persons. 2) Just because God uses examples (or illustrations or metaphors or analogies, etc.), doesn’t mean we can freely add ones He did not provide. To some extent, it might be natural to want to employ these devices—I think of the many attempts at finding a helpful analogy the Trinity—but we should remember certain things that would make us loath to add to these devices
First, we are not operating at the level of sermon illustrations, or at the level of exegeting individual passages of Scripture. Rather, these are issues of systematic theology.
And it is at this level that I was not comfortable with your example/illustration/metaphor/analogy of the Holy Spirit as the heart of God. I am no more comfortable with your example/illustration/metaphor/analogy of the Father as the brain of God, or with your example/illustration/metaphor/analogy of the Son as the body of God.
What legitimate doctrines of the Church are clarified by these examples/illustrations/metaphors/analogies? Similarly, what doctrines are clarified by your example/illustration/metaphor/analogy of “our spirit as our spiritual hearts”? That seems very Watchman Nee-ish to me (who, as far as I am concerned, wrote a lot of bad theology). And whether it is Watchman Nee-ish or not (indeed, whether you are familiar with him or not), the question stands: what doctrines does your example/illustration/metaphor/analogy help clarify?
"When the Round Table is broken every man must follow Galahad or Mordred; middle
things are gone." C.S. Lewis
“The chief purpose of life … is to increase according to our capacity our knowledge of God by all the means we have, and to be moved by it to praise and thanks. To do as we say in the Gloria in Excelsis ... We praise you, we call you holy, we worship you, we proclaim your glory, we thank you for the greatness of your splendor.” J.R.R. Tolkien