While discussing the eternal union of Human and Divine in the Son, I had to ask how we describe that to other people (Christians and non-Christians), since we consider Jesus to retain His human body and nature even now (Divine and Human eternally joined), without anthropomorphizing the rest of the Godhead (the Father and the Spirit). So, we spent at least half an hour on this (instead of studying Revelations...) and here is what we determined. Interestingly, Pastor felt like he didn't answer my question, but he definitely did. It just took me until the drive home to realize it.
The Trinity and who God is basic Christian doctrine that almost everyone, regardless of denomination, agrees upon (sans the heretics). However, it is also unbelievably complex and not particularly logical in a mathematical sense, for example (Pastor said that after this discussion, we can all graduate Seminary because of the complexity of the topic we just discussed...). It makes sense to me, but that is largely because of faith. To be fair, from a human perspective, I can more than understand why a non-Christian would look at this and think we're nuts.
Pastor Wolfmueller's lovely illustration.
Edit: Thanks to Becki for a link the the image my Pastor was referencing here.
First, for clarity, the Persons of God within the Trinity are the Father, the Son, and the Spirit. Each Person of the Trinity has the full Essence of God. The Son has two Natures: fully God and fully Man, or both Divine and Human. So that is what I mean by those terms when I use them below.
The Essence of God:
God is the Father. The Father (A) is God (D). (A = D)
God is the Son. The Son (B) is God (D). (B=D)
God is the Spirit. The Spirit (C) is God (D). (C=D)
However... the Persons of God within the Trinity:
The Father is not the Son, and the Son is not the Father. (A ≠ B and B ≠ A)
The Son is not the Spirit, and the Spirit is not the Son. (B ≠ C and C ≠ B)
The Spirit is not the Father, and the Father is not the Spirit. (C ≠ A and A ≠ C)
The Natures of God:
The Father is fully Divine in Nature.
The Son is both fully Divine and fully Human in Nature (Personal Union).
The Spirit is fully Divine in Nature.
God is fully Divine in Nature, joined through the Son to humanity.
Additionally, all Persons of the Trinity are co-equal and co-eternal (no one is above the others, and no one existed before the others). However, we would say that the Father beget the Son (that both name are essential to the Persons of that member of the Trinity) and that the Spirit proceeds from the Father AND Son--while all three remain co-equal and co-eternal, always existing together and without "rank" in the Godhead.
All of which brings us to my question, which essentially is how to describe the Nature of the Son as being separate from the other Persons of the Trinity without being separate from Essence of God, which all three persons of the Trinity share in full.
When the Son took the form of flesh (fully God and fully Man), did the essence of God change (since the Father, Son and Spirit are all fully God)? No, because the Divine = the Flesh in the Son, but the Flesh ≠ the Divine in the Son. This, by the by, was the answer to my question: because the Son is fully Divine, therefore fully God, God is joined into humanity in the Son, but since neither the Father nor Spirit are the same as the Person of the Son, they cannot be joined in humanity as well, even though both, like the Son, are also fully God.
This is also the reason we (meaning Roman Catholics, Eastern and Oriental Orthodox, Lutherans and Anglicans) can, should, and do call Mary the Theotokos ("God-Bearer" or Mother of God) rather than those (all not listed above--basically, protestants and heretics--not implying that the two are the same) who would call her Christotokos ("Christ-Bearer" or Mother of Christ)--because Christ is fully Divine, and therefore fully God in Essence and Nature. Nota Bene: the Council of Ephesus in 431 declared "Christotokos" to be heretical.
For more on how all this works, the Athanasian Creed (written to combat Arianism, which denies the Divinity of Jesus, as well as those accusing Christians of polytheism--the worship, in Christianity's case, of a Trinity of gods, instead of the Trinity in one God) does a beautiful job of explaining "one God in Trinity, and Trinity in Unity." It's more lengthy than the Apostles' or Nicene-Constantinople Creeds, which is why the Lutheran Church at least only uses it on Trinity Sunday, but it is the most succinct, yet thorough, explanation of the Persons, Essence and Natures of God in the Trinity.
Finally, one of Pastor Wolfmueller's great observation was with regards to the question of "having a relationship with Jesus." Technically speaking, everyone has a relationship with Jesus, some are just very bad ones (i.e. non-believers). Christians don't really have a "relationship" with Jesus, though. No. Rather, through baptism, we are joined with Jesus, and we are one with Christ and become partakers of the Divine Nature (knows as the mystical union or mysterious union--2 Peter 1:2-4).
Just like the "So when were you saved?" question I despise, the "Do you have a relationship with Jesus?" question is on my "hate list" for questions asked by well meaning, but theologically illiterate, Christians. Both are totally the wrong question, a) because both emphasize your role in salvation (which is only to reject faith, but by emphasizing more than that, these questions are Arminianist, and therefore Synchronistic, and, consequently, heretical), and b) because the real questions are "When were you baptized?" and "Has the Holy Ghost worked faith in you?", respectively, if you must ask one of the two--although the latter here ("Has the Holy Ghost worked faith in you?") is often what is meant by the previous above ("So when were you saved?").