By P R O F E S S O R P A U L T R E B I L C O (Otago University)

One key feature of “local” experience for earliest Christians was the house
church. Let me note some vital characteristics of house churches. Firstly,
in the New Testament period and beyond, the early Christians met in
each other’s homes for teaching, for worship and for all facets of their life
together.15 Paul writes of a “house church” in 1 Corinthians 16:9: “Aquila
and Prisca, together with the church in their house, greet you warmly in
the Lord.” And note Colossians 4:15: “Give my greetings to the brothers and
sisters in Laodicea, and to Nympha and the church in her house.”16
So, for the earliest Christians, “church” meant “house church”, not a
particular building. The nucleus of the group would often have been a
particular household,17 although new converts from outside the household
and from non-Christian families would join the group. As Branick notes
“The private home … afforded a place of privacy, intimacy and stability for
the early Christians.”18 It was in the house church that the Lord’s Supper
was celebrated; since the Lord’s Supper was at this stage a full meal, and
since there is no hint in the two places where Paul speaks of it that the
management of the meal was in the hands of an official of any kind, the
person in whose house it was held probably made the arrangements for the
meal and had a presiding role over the Lord’s Supper.19

The size and structure of house churches had a considerable impact on
church life. The maximum size of any house church depended on the
number of people that could be accommodated in the largest house owned
by one of its members. The average size of a house church is debated, and
clearly relates to the size of houses in different places and the relative wealth
or poverty of members of the church. however, the average number of
people that could be accommodated in a wealthy person’s house is probably
30-40,20 but we should certainly not think that every house church had a
person of this sort of wealth amongst its members. Clearly some house
churches would be much smaller. It is also clear that several house churches
came to exist in some cities.21

My point here is that “community” or “church” for the early Christians was
focussed predominantly on the home. This led to a strong familial ethos; it
is closely connected to the fact that by far the most predominant form of
address in the New Testament is “brother and sister”. This was what they
called each other. The use of kinship language reflects a tight and intense
community, and it stems in part from the location in the house church.
All this means that the sense of being a community here, was very powerful.
It was “church” experienced in the home, in the dining room. The house
church shaped early Christian experience, for it was an intense and “placeoriented”
expression of Christian faith. They belonged together, as a
household community, in Jerusalem, or Ephesus, or Rome.

read the whole article here http://www.otago.ac.nz/news/inaugural_lectures/2006/Trebilco.pdf