Hello @IlovelivingforJesus, here's a comparison of the KJV's v7 with the NASB's v7 (both with a little context). The difference is stunning (principally because of what the AV includes that most other translations do not).
I've also included the notes from the KJV Bible Commentary just below the Bible passages and was surprised to see how strong of a stance they took against the KJV's wording of v7. I read where some believe the v7 additional words to be sound based upon the "obvious" referral to the Trinity in v6. What say you
1 John 5 KJV
5 Who is he who overcomes the world, but he who believes that Jesus is the Son of God?
6 This is He who came by water and blood—Jesus Christ; not only by water, but by water and blood. And it is the Spirit who bears witness, because the Spirit is truth.
7 For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit; and these three are one.
8 And there are three that bear witness on earth: the Spirit, the water, and the blood; and these three agree as one.
1 John 5 NASB
5 Who is the one who overcomes the world, but he who believes that Jesus is the Son of God?
6 This is the One who came by water and blood, Jesus Christ; not with the water only, but with the water and with the blood. It is the Spirit who testifies, because the Spirit is the truth.
7 For there are three that testify:
8 the Spirit and the water and the blood; and the three are in agreement.
KJV Bible Commentary
1 John 5:6–8. John now gives a description of Jesus Christ as he that came by water and blood. No one knows (now) exactly what John had in mind when he used these two symbols. Tertullian’s guess seems to fit the facts best: the water is a reference to His baptism or inauguration, where the Voice from heaven declared, “This is my beloved Son,” and established that Jesus was the Christ. The blood is a common symbol for His death, where there were also supernatural miracles to cause even the confirmed and cruel Roman centurion to realize that this man (Jesus) was more than a mere man (Mt 27:54); also, by the Resurrection, the Father confirmed Jesus as the Son of God (Rom 1:4). This interpretation also fits the facts concerning the gnostic-type beliefs of Cerinthus who taught that the Christ came upon Jesus at the baptism but left Him before the Cross; John could have been refuting some such heresy. It is interesting that John called attention to the water, and the blood which came from the side of Jesus on the cross (Jn 19:34–35). At any rate, these were important symbols or witnesses to the deity of Christ in John’s mind. He also adds a third witness, the indwelling Spirit. Thus, according to John’s count here, there are three that bear record. The rest of verse 7 and the first nine words of verse 8 are not original, and are not to be considered as a part of the Word of God (refer to the marginal notes in any reference Bible). John’s three witnesses then are: the spirit, and the water, and the blood: and the three agree in one. Agree in one is an idiom which is properly translated simply, agree. Only two or three witnesses were needed to establish the truth of a fact (Deut 19:15; Jn 8:17). ~Hindson, E. E., & Kroll, W. M. (Eds.). (1994). KJV Bible Commentary (p. 2638).
God bless you!
~Deut