I'm not letting Trinitarianism beat me into just admitting that it's impossible, so I've come up with a potential explanation for it. Modalism is the belief that the 3 persons of God are separate states of God, sort of how water is liquid at the bottom of the sea, ice near the surface of the poles, and gaseous vapor in the atmosphere. Partialism is the belief that the 3 persons of God are each individual parts of the Godhead which, together, make God. According to Agrippa's Occult Philosophy, there are layers to our reality, we can call them "planes" although he didn't use this term. He actually lists four planes; celestial, intelligent, terrestrial, and infernal, corresponding to the realm of archangels, angels, fallen creation, and demons, respectively. For the sake of comparison, we can just focus on the first three, which are elsewhere seen as the layers of the Trinity. Essentially, we have God the Father associated with the top plane, the Holy Spirit as the intermediary, and God the Son as its manifestation in the terrestrial realm. If we see "God" as an entity that exists on all 3 levels, we can see each of the 3 persons as corresponding to God's manifestation in each realm, thus we have a form of Modalism. However, if each lower plane is merely an imperfect reflection of the higher one, as it is often seen in Platonism, then there really isn't 3 separate modes of being but 1 Godhead in 3 persons. Jesus, therefore, isn't just part of God but is wholly God as a reflection of God cast on the mirror of the terrestrial realm. The only thing that's really "divided," then, is the world itself which, in its fallen state, has grown more distant from God. Yet, at the same time, God's light continues to reflect in this world, making God still technically omnipresent. I don't know how well this works but it's the best explanation of the Trinity that I can come up with. It's essentially God looking in a three-part mirror.