Jesus said “I am in the Father and the Father is in me”. John 14:1NIV How is Jesus in the Father? This scripture could not be teaching that Jesus is physically inside the Father because Jesus was on earth when He said this. We know God dwells in heaven on His throne. If Jesus was not physically in God, then how? 

Jesus also said the Father is in me. How was God in Jesus? Again, this can’t mean that the Heavenly Father was literally inside Jesus. A human body could not possibly contain God. But God can be in Jesus’ mind and heart. Their union is a union of purpose. Jesus talked about how closely He followed His Father’s will in John 6:38, “For I came down from heaven, not to do mine own will, but the will of him that sent me.” Hebrews 10:9, “Then said he, Lo, I come to do they will, O God.” Additionally, Jesus said the works he performed and even his very words were all from God. John 14:10, “the words that I speak unto you I speak not of myself: but the Father that dwelt in me, he doeth the works.” 

Jesus wanted His followers to share in this wonderful unity. “I am in the Father, and ye in me, and I in you.” John 14:20.

God and Jesus are both dwelling in us when we try to do and obey His will. “Jesus answered…If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.” Yes, it is when we read the Bible and then apply these truths to our lives, that we are living in Him, and God and Jesus are living in us.

It may be helpful to remember times when we have sinned. We will feel sorrow, distanced from God. Likewise, when we are living in obedience to God's will, we feel communion and closeness with Him. This is the experience of oneness.

The Holy Spirit is divine power and influence. It is called by many different titles: “The Spirit of God,” “The Spirit of the Father,” “the Spirit of Christ,” “the Spirit of Holiness,” “The Spirit of Truth,” “The Spirit of a Sound Mind,” “The Spirit of Liberty,” “The Holy Spirit of Promise,” “The Spirit of Meekness,” “The Spirit of Understanding,” “The Spirit of Wisdom,” “The Spirit of Glory,” “The Spirit  of Counsel,” “The Spirit of Grace,” “The Spirit of Adoption” and “The Spirit of Prophecy.”

These various titles are expressions of the influence and power of God, the Father and of Jesus, the only begotten son (see KJV, John 3:16). It is only through the power of the Holy Spirit that we are able to be united as the body of Christ, “For by one Spirit are we all baptized into one body” (1 Cor. 12:13). We are united with God and Jesus in purpose. “For as many as are led by the Spirit of God, they are the sons of God.” Rom. 8:14.

The word Trinity actually does not appear in the Bible. Additionally, the concept means different things to different people. However, as shown above, there are many verses which illustrate the unity of God, the Father; Jesus, His only begotten Son; and the Church. They are united in purpose of heart, mind, and works through the power of the Holy Spirit.