Most of the churches I attended in my life had something called “fellowship” and some even had space dedicated to it called “fellowship hall” or something similar. We had time after “church” that was called “fellowship time” that always seemed to be a relaxed time of visiting together and just being friendly with each other outside of normal “church stuff.” In the New Testament the word that is translated as “fellowship” as in Acts 2:42 (above) is κοινωνίᾳ (koinōnia), which Greek scholar Kenneth Wuest defined as, “joint participation in a common interest or activity.”…
Instead of simply a friendly time of visiting together or a coming together for relaxation, κοινωνίᾳ, then, is a partnership, a sharing of something in common.
42 And they were devoting themselves to the teaching of the apostles and to the fellowship, the breaking of the bread and to prayers. Acts 2:42 (translated from the NA28 Greek text)
In this verse we have the fourfold activity of the church. The believers continued steadfastly in the teaching or doctrine of the apostles and fellowship, and in breaking of bread, and in prayers. It should be clear that these believers were not divided in any way. They had a single-mindedness to stand firm in what the apostles were teaching them and in doing that they partnered together to do so. In this they broke bread together and, of course, prayed together. There was a close communion with each other. This partnering together, this fellowship is second only to the foundational element of doctrine and teaching. It is crucial that Christians fellowship with one another.