John 10:38 says, "...Then you will realize that the Father is in me, and I am in the Father." (NLT)
Some claim that this Scripture is proof that Jesus is God or of the Trinity.
But if someone is "in" someone else does this really mean that they ARE that person? If so, then does that mean that those who Jesus were talking to in John 14:20 who were "in" Jesus ARE also Jesus? Or in verse 17, that because the Holy Spirit was "in" them that they ARE the Holy Spirit?
And is this really supposed to imply that Jesus IS the Father here? Even Trinitarians don't believe that the Son IS the Father. They believe that the Son is a separate and distinct individual, the Father is a separate and distinct individual and that the Holy Spirit is a separate and distinct individual who all three somehow make up the One True God.
We can understand what Jesus actually intended when he said "I am in the Father and the Father is in me" and "the Father is abiding in me." The relationship between "abiding in," "knowing," and "seeing" (horao in NT Greek) is commonly used FIGURATIVELY in the Bible. 1 John 2:3, 5, 6; 1 John 3:29 show the intended meaning for the figurative use of "abides." Horao ("see") can mean the same thing as "abiding in" or "knowing," and all three may have the figurative meaning of agreement in purpose and will with someone else.
There is no real reason to insist that this passage shows Jesus as being equally God with his Father. The probability is that, in harmony with the usage of the time, Jesus was merely saying that what he spoke came from God, and what he did is what God directed. He meant that understanding what he did and said was like knowing ("seeing") God (as, in a similar sense, those who literally saw angels sent by God and speaking God's words were said to have "seen God"). Jesus is totally in harmony with ("one" with) the Father in purpose so that we can "see" the Father's will in Jesus.
(Also see: In John 10:30, does Jesus say that he and his Father are one person?; Search For Bible Truths)
As in all other "Jesus is equally God" evidence, we find that the trinitarian "proof" is a Scripture that can honestly be translated or interpreted in at least one other way which would prove no such thing.
For more, see:
"Seen Me: Seen Father" - John 14:7-9 (Search For Bible Truths)
John 14:10 "Believest thou not that I am in the Father, and the Father in me? the words that I say unto you I speak not from myself: but the Father abiding in me doeth his works." - ASV.
In What Way Are Jesus and His Father One? (w09 9/1 p. 28; Watchtower Online Library)