If me and you and another friend saw an accident. We must appear in the court, shall we be three in one, or are we are witnesses at the same spot?
God = The God
Jesus = The God Son and is automatically God.
Holy Spirit = Their Spirit, their own life. Their power, that's why it is everywhere. It is their breath/mind, something that belong only to them. And when we received their Holy Spirit in us, than ot isn't more that are speaking, but it is the Holy Spirit that are speaking to the one that are listening.
You are viewing this as what is taught in your religion that God, as the Supreme Being of the universe, gradually acquired that position over a long period of time by living a perfect and righteous life and has a flesh and bone body. This is why you can not see that the Father, Son and Holy Spirit all equal God's Spirit as all three are co-equal as being God's Spirit.
1 John 5:6 This is he that came by water and blood, even Jesus Christ; not by water only, but by water and blood. And it is the Spirit that beareth witness, because the Spirit is truth.
1 John 5:7 For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.
1 John 5:8 And there are three that bear witness in earth, the Spirit, and the water, and the blood: and these three agree in one.
Water in these verses means living water as in the living word of God, John 4:4-26; 7:37-39; 12:44-50; Ephesians 5:26; 1 John 5:5-8; Jeremiah 17:13; Zechariah 14:8, 9; Rev 21:6-8; Ezekiel 47:22
Jesus is word, light and life that is God transfigured in the flesh.
John 1:1 In the beginning was the Word, and the Word was with God, and the Word was God. 2 The same was in the beginning with God. 3 All things were made by him; and without him was not any thing made that was made. 4 In him was life; and the life was the light of men.
Gods Holy Spirit has come to indwell us and teach us. John 14: 26 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.
It's all God's Spirit manifested in the flesh of Christ and the Holy Spirit being God's Spirit that indwells us. All three, Father, Son and Holy Spirit, are existence, being, and life that make up the full Godhead. Can we comprehend all of this, no, as we can only know in part until Christ returns and then we will understand the full when we are with Him in the New Jerusalem.
John 10:30 I and my Father are one.
John 14:9 Jesus saith unto him, Have I been so long time with you, and yet hast thou not known me, Philip? he that hath seen me hath seen the Father; and how sayest thou then, Shew us the Father?
John 14:10 Believest thou not that I am in the Father, and the Father in me? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works.
I Am who I Am. This name tells that God is beyond definition, comparison and no limiting name could ever be given Him. He is self-existent and eternal. Exodus 3:14; 6:2; Isaiah 40:28; John 8:58; 10:30; 14:6; 20:28; Rev 19:6.
Colossians 2:9
For in him dwelleth all the fulness of the Godhead bodily