Christians enjoy interaction with the Father and the Son. Obviously such vertical fellowship involves more than an awareness of correct doctrine about Jesus. In addition, there will be adoration and affection. Fellowship involves expressions of wonder and love. There are many ways in which believers can have fellowship with the Father and the Son. John’s description indicates that we can have simultaneous fellowship with them and that we can also have distinct fellowship with each of the divine persons. He also indicates that this vertical fellowship can be corporate, as in a church gathering, or it can be an individual interaction with them.
Here is an example of vertical fellowship. We have been reconciled to the Father through the work of the Son on the cross. This reconciliation was planned by the Father and the Son in eternity and it involved the Son bearing the wrath of the Father against our sins. We came into the state of reconciliation when we believed in Jesus and were recognised as justified by the Father. And we can speak to the Father and the Son in peace, which is fellowship.
Another example of vertical fellowship takes place when disciples focus on the fact that they and God now belong to the same family. Prior to believing in Jesus they were not members of the family of God. Instead they were outcasts, the children of wrath. On believing, they were adopted by the Father and became brothers of the Son. As God’s children they were given a right to all the privileges of the sons of God; in fact, each of them became a joint-heir with Jesus of the heavenly inheritance. And they can interact with the Father and the Son in this area of fellowship.
There are many aspects to the fellowship that believers share with God as members of the heavenly family. One great blessing is prayer by which they draw near to the heavenly Father and present their petitions in the name of the Son. Another blessing is that they are able to reflect on and experience partial fulfilments of the great promises of God that are theirs because they have been purchased for them by Jesus through his work on the cross. A third blessing concerns their anticipations of the future, of the great endless period ahead when they will enjoy with the Father and the Son the fullness of the heavenly inheritance.