An interesting observation from Justo Gonzales (Faith and Wealth, p. 83):
Gonzales notes that the work koinonia is usually translated as “fellowship” or “brotherhood,” typically understood to mean “an inner disposition of goodwill.” Yet the word means so much more. Gonzales writes,
Koinona means first of all, not fellowship in the sense of good feelings toward each other, but sharing. It is used in that sense throughout the New Testament, both in connection with material goods and in other contexts. In Philippians 3:10, what the Revised Standard Version translates as “share his sufferings” actually says “know the koinonia of his sufferings.” In 1 Corinthians 10:16, Paul says “The cup of blessing which we bless, is it not a participation in the body of Christ? The bread which we break, is it not a participation in the blood of Christ?” The term that the Revised Standard Version translates here as “participation” …. is koinonia. Paul’s letter to the Philippians, which acknowledges receipt of a gift, begins with words in which Paul is thanking the Philippians for their partnership and sharing with him. In 1:5, he says that he is thankful for the Philippians’ koinonia, and two verses later he declares that they are “joint koinonoi” of grace with hi, that is, common owners or sharers. At the end of the epistle, he says that they have shared in his trouble (4:14), and the term he uses could be translated as “cokoinonized.” All of this leads to the unique partnership “in giving and receiving” that he has enjoyed with the church of the Philippians (4:15), and once again the word he uses literally means “koinonia.” In short, koinonia is much more than a feeling of fellowship; it involves sharing goods as well as feelings.
Returning to Acts 2:42, it is clear that kononia there is much more than fellowship: “They devoted themselves to the apostles’ teaching and koinonia, to the breaking of bread and prayers.” The four things listed here, the apostles’ teaching, koinonia, the breaking of bread, and prayers, are taken up in almost the same order in verses 43 to 47, where we are told (1) that fear came upon every soul, and wonders and signs were done through the apostles; (2) that all who believed had all things in common; (3) that they attended the temple and praised God; and (4) that they broke bread in their homes and partook of food with glad and generous hearts. The koinonia is not simply a spiritual sharing. It is a total sharing that includes the material as well as the spiritual.