The Book: The Apostles, Pope Benedict XVI a must read. Relevant Excerpt

On discipleship, fellowship and witnessing, this is Cornerstone.  Seeing the image of God within our fellows and our self. 

The idea of communion as participation in Trinitarian life is illuminated with special intensity in John’s Gospel.

            Here, the communion of love that binds the Son to the Father and to men and women is at the same time the model and source of the fraternal communion that must unite disciples with one another: “Love one another as I have loved you;” “that they may all be one even as we are one.”  Hence, it is communion of men and women with the Trinitarian God and communion of men and women with one another.

            During the time of his earthly pilgrimage, the disciple can already share through communion with the Son in his divine life and that of the Father, “our fellowship is with the Father and with his Son Jesus Christ.”

            This life of fellowship with God and with one another is the proper goal of the Gospel proclamation, the goal of conversion to Christianity: “That which we have seen and heard we proclaim also to you, so that you may have fellowship with us. 4For our fellowship is with the Father and with his Son, Jesus Christ.  We are writing this (we Cornerstone men are saying this) so that our joy may be complete.”
(1 Jn 1:3-4)

From The Apostles written by Pope Benedict XVI

Embolden  lines of 1 John are not in the book, but relevant to our discipleship.