“The unity of the Spirit” is much deeper than feelings of acceptance. Consider Paul’s reasoning in 1 Corinthians 12:14-16.
For the body does not consist of one member but of many. If the foot should say, “Because I am not a hand, I do not belong to the body,” that would not make it any less a part of the body. And if the ear should say, “Because I am not an eye, I do not belong to the body,” that would not make it any less a part of the body.
My fleshly body has complex systems. Each system has many components. Yet I have just one body. So it is with Christ’s spiritual body. Suppose, as a Christian, I seem like a misfit. Other members ignore me, and I feel isolated. Does that make me any less a part of Christ’s body? No. My earthly feelings, whether positive or negative, do not determine heavenly realities. There was a time when Paul said, “all deserted me” (2 Timothy 4:16). Yet he was still secure in his relationship with the Lord (2 Timothy 1:12; 4:8, 17-18). What matters is the Lord and how He sees me (1 Corinthians 4:3-4; 2 Corinthians 12:19; 2 Timothy 2:19). If I have obeyed the Gospel, He has added me to His church and He values my place in it. The blood of this body is His cleansing blood. It flows in every part of the body regardless of what others think about that part.
“There is one body and one Spirit.”
Similarly, I am a spiritual being. My spirit has a fleshly body. When they become separated, my body loses its life. “The body apart from the spirit is dead” (James 2:26). It is not accidental that the “ones” of Ephesians 4 begin with this couple: “There is one body and one Spirit” (Ephesians 4:4). The body and the Spirit go together. The Holy Spirit gives life to the body, the church. He is present in each individual who makes up the body. No member of Christ is left out. “Anyone who does not have the Spirit of Christ does not belong to Him” (Romans 8:9).