In the history of theological study concerning the divine Trinity, three words have been used—essence, hypostasis, and substance. We need to clarify the meaning of these three words, which we have already mentioned in relation to the divine Trinity.
We can see what the word essence means in the study of the divine Trinity by defining two related words—element and nature. An element is a substance. In the New Jerusalem there are three elements—gold, pearls, and precious stones. Therefore, in the building of the New Jerusalem there are three substances or elements. Every element has its nature and in the nature of the element is the essence. Consequently, the essence denotes the very thing itself. Now we can see that there is a difference in using the two words essence and substance. We cannot refer to the substance of the essence but to the essence of the substance. Each substance or substantial element has its essence.
It is clearly revealed in the Bible that God is an eternal God. The eternal God has His existence and with His existence there must be the essence. Without essence there is not existence. Anything that exists has an essence, so essence actually refers mostly to God’s existence. Our God is the eternal God existing from eternity to eternity. His existence tells us that He has the essence which we call the divine essence.
Another word used in relation to the Trinity is hypostasis. This anglicized Greek word is actually composed of two Greek words—hupo meaning under or below and stasis meaning substantial support. The word, therefore, means the substantial support underneath. This is like the four legs of a table being the substantial support underneath. Hypostasis in English simply means substantial support. The Father, the Son, and the Spirit are the three hypostases or substances of the divine Trinity or of the Godhead.
Gradually, however, this word has been used in the sense of person. This understanding is far off and causes trouble. To say that the Father, the Son, and the Spirit are three hypostases is correct, but to say definitely that the Father, the Son, and the Spirit are three persons is going a little too far. Griffith Thomas indicated that we may borrow a word like person to define the Trinity because our human language is inadequate, but if we press the term person too far, it will lead to tritheism. Even to use the word hypostasis is not completely safe because when we use any terms, vocabulary, or illustrations to define the divine Trinity, we always run a risk. The divine Trinity is too much of a mystery. Our finite mentality is incapable of understanding the divine Trinity in full. We do not have the adequate vocabulary to describe Him because in our human culture there is not such a mysterious thing as the divine Trinity. Because there is not such a thing, we do not have the vocabulary, and even in our mentality we do not have the logic to understand the divine Trinity.
In the historical study of the divine Trinity, the word hypostasis was first used and then the word substance. Hypostasis and substance are synonyms in theological study. Then the word essence was picked up. In the substance there is the essence. In the study of the divine Trinity the following crucial statement was made—the Triune God has three substances but only one essence. This statement is more safe. The Triune God is essentially one but substantially three. The Triune God is one in His essence, but He is three in His substance. To say that God has three essences is wrong, but to say that God has three substances is correct. Three substances equals three hypostases and, as some say, three hypostases equals three persons. Therefore, substantially speaking God is three, and essentially speaking God is one. This is the essential Trinity. In essence, the Father, the Son, and the Spirit are one, but in substance (person) They are three. Actually, we do not appreciate the word persons that much. Rather, we appreciate the word hypostases. I hope this fellowship has provided “a simple map” of the understanding of the words element, nature, essence, substance, hypostasis, and person.
Also, God is very purposeful. Ephesians 1 reveals that God has His good pleasure, His heart’s desire (vv. 5, 9). God made a purpose according to His good pleasure, which is His heart’s desire. He is a living God and very purposeful. Such a purposeful God surely has a desire. He wants something and He wants to do something, so He made a plan. This plan needs to be accomplished, and to carry out the accomplishment of this plan many works are needed. God made a plan with an arrangement to fulfill His purpose according to His desire. This plan, this arrangement, is His economy, His oikonomia, His household arrangement, His household administration.
In God’s economy there are three steps or stages. The first step was taken by the Father, the second step was taken by the Son, and the third step was taken by the Spirit. In each step of this successive economy there are some works to be accomplished.