Fellowship

1 John 1v3

The word fellowship is an interesting one. Used in classical Greek as a favorite expression for the marriage relationship, the most intimate bond between human beings, it is particularly appropriate to describe the Christian's personal relationship with God and with his fellow believers as her and later in verse 6 and 7. But the word also meant a participation or sharing in a more general sense, for instance a business partnership or a joint tenancy. Perhaps John could look back on the distant days when he and his brother James had been shareholders in the Zebedee Fishing Company. 

p24 The Message of John's Letters: Living in the Love of God (Bible Speaks Today)


In Luke 5:10 it is used to describe the relationship between fishermen who worked together as business partners. 
In Matthew 23:30 Jesus uses it to describe how the Pharisees deny that they would have been fellow-murderers with those who killed the prophets. 

John on John

It is the direction in which our life is travelling which determines whether or not our Christian profession is genuine. ... 

Perhaps John Newton, the converted slave-trading sea captain, who became a minister of the gospel, expressed it most helpfully when he said,'I am not what I ought to be; but I am not what I once was. And it is by the grace of God that I am what I am.'
p43 The Message of John's Letters: Living in the Love of God (Bible Speaks Today)

The signs of life

If John's purpose in his Gospel is so to witness to Christ that his readers will believe in him and receive life (20:31), his purpose in his letters ... is to take his readers a step further. He writes, 'to you who believe in the name of the Son of God so that you may know that you have eternal life' (1 John 5:13). For it is one thing to receive life; it is another to know that we have received it. So having assembled the seven signs which witness to Christ, John now develops three tests which undermine the false assurance of counterfeit Christians and confirm the true assurance of genuine Christians. He does not mince his words. He identifies three liars. First, whoever denies that Jesus is the Christ come in the flesh is a liar (1 John 2:22). This is the doctrinal test. Secondly, whoever claims to enjoy fellowship with God while walking in darkness lies(1 John 1:6). This is the moral test. Thirdly, whoever says he loves God but hates his brother is a liar (1 John 4:20). This is the social test. Conversely, (1) we know the Spirit of God, because he acknowledges Christ (1 John 4:2; cf. 2 John 9); (2) we know that we know him, because we obey his commandments (1 John 2:3) and (3) we know that we have passed out of death into life, because we love our Christian brothers and sisters (1 John 3:14). John even assembles three verbs which characterize God's people: they believe in Christ, they love one another, and they obey his commands (1 John 3:24-24). (The Incomparable Christ, Stott p 40)