GOD is mystery and beyond human intellect unless He reveal His personality to whoever He wants.

Colossians 2:2-3 That their hearts might be comforted, being knit together in love, and unto all riches of the full assurance of understanding, to the acknowledgement of the mystery of God, and of the Father, and of Christ;
In whom are hid all the treasures of wisdom and knowledge.

Man is a replica of the image of GOD.
And when we say "GOD", we are talking about a mysterious personality.
From the beginning, man know that there is GOD and as the Israelites were made to know, GOD IS ONE.

John 4:24 God is a Spirit: and they that worship him must worship him in spirit and in truth.

Firstly, we must believe that GOD is a Spirit. And in Spirit realm, there is a very broad perspective of things, which is different and extended beyond the physical realm and aspect. If we are to compare GOD to physical or mortal being, many things will remain unbelievable, for the flesh has limits, but the Spirit does not.

Deuteronomy 6:4 Hear, O Israel: The LORD our God is one LORD:

We know and believe GOD is One. But what some have not been able to understand is that, right in the One(GOD the FATHER) are two other personalities which He also included and revealed in humans as spirit, soul and body.

John 1:1-3 In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by him; and without him was not any thing made that was made.

Meaning the Word(JESUS CHRIST) was WITH GOD(the FATHER) and also at same time the same Word was GOD, because He is right inside the FATHER and by the same Word of the FATHER all things were created according to the will of the FATHER.

During the creation, we always read that, "GOD SAID LET THERE BE…" then we read, "AND GOD CREATED…" then we see what follows like after inspection, "AND GOD SAW THAT IT WAS GOOD." Which shows clearly that there is something not explained there which is:

"AND GOD SAID LET THERE BE..." - FATHER SPEAKING AND ISSUING OUT THE WORD.
"AND GOD CREATED..." - THE WORD CREATING AND CREATED IT.
"AND GOD SAW THAT IT WAS GOOD..." - THE HOLY GHOST INSPECTED WHAT THE WORD HAD CREATED AND CERTIFIED IT GOOD. The same as seen here:

Genesis 1:2 And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.

(NOTE: Both the Word and Holy Ghost are right inside the FATHER just as our LORD JESUS CHRIST made us know several times that He is in the Father.)
Which shows all three were working together with each taking a different role.

Now, when our LORD JESUS CHRIST came, before He left, He made us realize something about GOD here:

Matthew 28:19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:

Which means three personalities but yet in One.

And said here: John 10:30 I and my Father are one."

Now after GOD had created everything else, GOD, the Counselor raised a suggestion which was approved instantly by GOD as recorded here:

Genesis 1:26-27 And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth. So God created man in his own image, in the image of God created he him; male and female created he them.

Which means GOD the Counselor(JESUS CHRIST) was speaking to someone here who is GOD, in GOD and GOD.

Now, after creating man in His likeness and image, GOD still used the same replica of Himself on man, hereby making man of spirit, soul and body.
The body carries the other two in itself.
The other two can go out and return again into the body.

Same way JESUS CHRIST the Word came out of the FATHER after being sent by the FATHER and came to the world while the HOLY GHOST(Comforter) comes and takes over after the ascension of the Word, JESUS CHRIST.

Just as GOD(the FATHER) testified concerning His Word (JESUS CHRIST) here:

Isaiah 55:11
So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper in the thing whereto I sent it.

Do not be confused nor surprised when our LORD JESUS CHRIST was still on earth, He always say of the FATHER in Heaven, prays to the FATHER in Heaven, glorifies the FATHER in Heaven, and moreso, testified several times that the FATHER in Heaven sent Him, a fulfillment of Isaiah 55:11 but that He didn't come to do His own will but the will of the FATHER that sent Him.

John 6:38
For I came down from heaven, not to do mine own will, but the will of him that sent me.

Likewise, He made several emphasis on He being sent by the FATHER,

John 6:39
And this is the Father's will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day.

John 4:34
Jesus saith unto them, My meat is to do the will of him that sent me, and to finish his work.

John 5:23
That all men should honour the Son, even as they honour the Father. He that honoureth not the Son honoureth not the Father which hath sent him.

John 5:30
I can of mine own self do nothing: as I hear, I judge: and my judgment is just; because I seek not mine own will, but the will of the Father which hath sent me.

John 5:36
But I have greater witness than that of John: for the works which the Father hath given me to finish, the same works that I do, bear witness of me, that the Father hath sent me.

John 5:37
And the Father himself, which hath sent me, hath borne witness of me. Ye have neither heard his voice at any time, nor seen his shape.

John 8:42
Jesus said unto them, If God were your Father, ye would love me: for I proceeded forth and came from God; neither came I of myself, but he sent me.

Your soul is the real you.
The spirit GOD fixed in you to make you a living soul is in you.
And these two are in your body.

Now, GOD(the Word, the Son, even JESUS CHRIST) came from GOD(the FATHER) according to the will of the FATHER, His arrival arranged by the HOLY GHOST, descended to this earth on His mission of salvation and redemption of men from sin as pure and unstained blood is required for atonement of sin for as it is written:

Hebrews 9:22 And almost all things are by the law purged with blood; and without shedding of blood is no remission.

Here is why our LORD JESUS CHRIST had to come, for a one time atonement once and for all.

Because in those days, the blood of beasts were used as atonement which is done yearly,

Hebrews 9:7
But into the second went the high priest alone once every year, not without blood, which he offered for himself, and for the errors of the people:

Hebrews 13:11
For the bodies of those beasts, whose blood is brought into the sanctuary by the high priest for sin, are burned without the camp.

But our LORD JESUS CHRIST did it only once and for all.

Hebrews 13:12
Wherefore Jesus also, that he might sanctify the people with his own blood, suffered without the gate.

And after He had accomplished His mission successfully, He said:

John 20:17
Jesus saith unto her, Touch me not; for I am not yet ascended to my Father: but go to my brethren, and say unto them, I ascend unto my Father, and your Father; and to my God, and your God.

Before our LORD JESUS CHRIST left, He promised to pray the FATHER to 'send' His HOLY SPIRIT, who is also called the HOLY GHOST unto us. Here, our LORD JESUS CHRIST made us understand that this is the Spirit of Truth, meaning His Spirit, for JESUS CHRIST is the Truth and He is GOD.

John 14:16-17, 26 And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.
But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.

The same HOLY SPIRIT is our seal even unto the day of redemption.(The day our LORD JESUS CHRIST will return.)

Ephesians 4:30 And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption.

Understanding the mystery of the personality of GOD.