But fellowship is being in relationship with God. In the same way as it is possible for a son or daughter to be out of fellowship with their dad or mom, you and I can often times be out of fellowship with our Heavenly Father.
Fellowship is vital to relationship.
What is being referred to is something of a quite different order and on a quite different level. The early church met constantly to hear the apostles teach, and to share the common life, and break bread and to pray. A sense of awe was everywhere. All whose faith had drawn them together held everything in common. That is fellowship as the New Testament understands it, and there is clearly a world of difference between that and mere social activities.