Since the time of the Lord, the Christian church has passed through various ages; it has gone from infancy to extreme old age. Its infancy occurred when the apostles were alive and were preaching two things throughout the whole world: repentance and faith in the Lord God the Savior, as one can see from these words in the Acts of the Apostles: “To both Jews and Greeks Paul proclaimed repentance before God and faith in our Lord Jesus Christ” (Acts 20:21).
It is worth noting that several months ago the Lord called together his twelve disciples, who are now angels, and sent them out to the entire spiritual world with the command to preach the gospel there anew, since the church established by the Lord through those disciples is so close to its end today that scarcely any of it remains in existence. Also worth noting is that the church’s deterioration was the result of its splitting the divine Trinity into three persons, each of whom is God and Lord.
As a result, a kind of brain fever spread throughout the whole theology and infected the church that calls itself Christian from the name of the Lord. I call it a brain fever because this development has so deranged human minds that they do not know whether there is one God or three. The mouth says there is one, but the mind thinks there are three. The mind, then, is at cross-purposes with its own mouth, and thought with its own speech; this results in no knowledge of God at all. The materialist philosophy that rules today has no other source. As long as “one” is what the mouth is saying and “three” is what the mind is thinking, do they not inwardly meet halfway and obliterate each other? Then if thinking about God occurs at all, it scarcely goes beyond thinking the word “God.” The word is denuded of any meaning that would entail actually having a concept of him.
Because the idea of God and every notion of him has been torn to pieces, I intend to discuss in sequence God the Creator, the Lord the Redeemer, and the Holy Spirit the Effecter, and then to discuss the divine Trinity, with the purpose of mending what has been torn. This mending will occur when human reason is convinced from the Word and its light that there is a divine Trinity; that it exists within the Lord God the Savior Jesus Christ like the soul, the body, and the effect of one person; and that the following statement in the Athanasian Creed is valid:
In Christ, God and a human being, or the divine nature and the human nature, are not two; they are in one person. Just as the rational soul and the flesh is one human being, so God and a human being is one Christ.
from True Christianity, Volume 1, Section 4