We proclaim to you what we have seen and heard, so that you also may have fellowship with us. And our fellowship is with the Father and with his Son, Jesus Christ. 1 John 1:3
Fellowship means we belong to each other in a relationship because we share together the common life and enabling grace of Jesus Christ.
The ultimate goal is to build up and enrich others in the things of Christ that we may all together experience the sufficiency of His life and tune our lives into His. We need others for that. As the early church was first devoted to the apostles’ teaching, they were also devoted to caring for one another and to sharing with one another what they were learning and what Christ was meaning to them
15 Rejoice with those who rejoice, weep with those who weep. Romans 12:14-16
Let us therefore learn to embrace our weaknesses, to admit our faults, turn from them, ask for forgiveness and thank our Savior for his loving sacrifice. This will lend itself to "oneness" with others and "oneness" with God and will strengthen our fellowship.