The matter of the Father, Son, and Spirit is revealed mostly in the Gospel of John. It shows us:

1. The Father is the source (13:3), the God whom no man has seen at any time (1:18; 5:37). All that He has is in the Son (16:15), He is expressed in the Son (14:7-11), and He does His works in the Son (14:10). He is the One hidden within, and the Son is the One manifested without; yet the One who is manifested without is the One who is hidden within—the two are just one (10:30)! Oh, how mysterious!

2. The Son is the expression (1:18). He is the God who was from the beginning and who was with God (1:1-2), equal with God (5:18, 23), one with the Father (10:30), come out from God (13:3; 7:29) to express the Father (14:8-9) and live by the Father (6:57), and finally in the flesh (1:14) as the Lamb of God (1:29) He was crucified and died, shedding His blood for redemption (19:34). After death and resurrection He became the Spirit breathed into the disciples (20:22). He became their life (10:10), and He became also the bread of life for them to eat and enjoy that they may live by Him (6:35, 57).

3. The Spirit is the entering in of the Son into us who believe in the Son to be in us the reality of the Son (14:16-20) and to communicate and impart to us all that He has received from the Son (16:13-15). The Father is in the Son (14:10-11), the Son became the Spirit for us to drink in as the water of life (7:37-39; 4:10, 14), and the Spirit comes into us and abides with us that we may enjoy the Son (14:17-18). The Spirit in us is the Son in us (14:17, 20; 17:23, 26). In this Spirit we are joined to the Triune God as one (17:21-23).

Thus, the Gospel of John shows us clearly that the Father is the source of all, the Son is the expression of the Father, and the Spirit is the coming in of the Son. In the heavens, where man cannot see, God is the Father; when He is expressed among men, He is the Son; and when He comes into men, He is the Spirit. The Father was expressed among men in the Son, and the Son became the Spirit to come into men. The Father is in the Son, and the Son became the Spirit—the three are just one God.

This matter of the Father, Son, and Spirit—the trinity of the Godhead—is one which we cannot use our mind to comprehend. When the Lord was in the flesh, He told the disciples clearly that at that time He could not speak much with them, for they could not bear it; but when the Spirit of reality would come, He would lead them into all reality (John 16:12-13). What He meant was that at that time He had not yet become the Spirit; so He could not come into them. He could only be outside of them. He had already told them much, and if He were to tell them more, their mind would not be able to comprehend. But when He would rise from the dead and become the Spirit to enter into them, He would then be in them and bring them into all reality to enjoy the Triune God. We cannot therefore simply use our mind to understand the mystery of the Father, Son, and Spirit. The conclusion of mental analysis is certainly that the Father is one, the Son is one, and the Spirit also is one; thus, the Father, Son, and Spirit are three Gods! This is the reasoned judgment of your mind. But if you check with your own experience, you will declare that the Lord who dwells in you is surely one. According to your mental understanding there are three Gods, but according to your experience there is but one. Therefore, do not count on your mental understanding, but on your experience. If you follow your mental understanding you will be puzzled, but by your experience you are clear that the Father, the Son, and the Spirit are the three persons of the one God.

The term three Persons does not exist in the Scriptures, but is added by men in their interpretation. Since they cannot say that the three—the Father, Son, and Spirit—are three Gods, what else can they say? So the designation three Persons is used. Actually, to use the designation three Persons to explain the Father, Son, and Spirit is also not quite satisfactory, because three Persons really means three persons. Therefore, Griffith Thomas (famous for his expositions on the book of Romans) in his book The Principles of Theology, wrote in this wise concerning the trinity of the Godhead: "The term 'Person' is also sometimes objected to. Like all human language, it is liable to be accused of inadequacy and even positive error. It certainly must not be pressed too far, or it will lead to Tritheism....While, therefore, we are compelled to use terms like 'substance' and 'Person,' we are not to think of them as identical with what we understand as human substance or personality....The truth and experience of the Trinity is not dependent upon theological terminology." Therefore, concerning the three Persons we can only say this much. We should not "press too far," or it will lead to tritheism.