Where did small groups start? Are cell groups (small groups, care groups) a New Testament pattern? Which denominations, other than the Methodists, promote the use of small groups?

Though there's a lot we don't know about the early church, we can learn a lot from the New Testament, especially the letters of Paul. Paul uses the word "ekklesia," which from pre-Christian days meant "any gathering of a group of people," to refer to a gathering of people before God. The gatherings were usually small, probably 30 members on average, and the people often belonged to the same household or guild. Sometimes several such groups met together, but this was probably rare before the third century, when special buildings for Christian worship began to be constructed.

Small groups of Christians met regularly (weekly or perhaps monthly) for worship, encouragement, and instruction as early as the first decades of Christianity, but it's not quite accurate to call them "small groups" in the contemporary sense. ...