Christianity is not an individualistic religion, but a new creation as the Body of Christ reconciled to the Father. That means that if we want to be joined to Christ who is the Head, we would need to be attached to other Christians as well who are part of the Body of Christ. Think of it this way; what will happen if a finger is amputated from a human body? Well the reality is that the amputated finger will wither away because it is separated from the life source of the body. Is it then possible that a member can only be a member of the head without having any relation to the rest of the body? No; he or she will wither away spiritually.
1Co.12:20 But now indeed there are many members, yet one body.
1Co.12:21 And the eye cannot say to the hand, "I have no need of you"; nor again the head to the feet, "I have no need of you."
In order for us to have a genuine relationship/fellowship with Christ, we have to have fellowship with the whole Person of Christ, which is Body, Soul and Spirit. John writing concerning Jesus the Word of life the following in:
1Jn 1:3 that which we have seen and heard we declare to you, that you also may have fellowship with us; and truly our fellowship is with the Father and with His Son Jesus Christ.