Why did the first believers talk together only in their own small groups?
The early believers had become separated from the mainstream of Judaism, so their only available setting for talking together was their own small fellowship groups. There they shared the Apostle's Doctrine, fellowship, breaking of bread, and prayer, since normal mainstream association was no longer their place of gathered converse.
Les explains that the believers in Acts 2 were devoted to the Apostle's Doctrine, fellowship, breaking of bread, and prayer—all very normal and common practices. But because they were now separated from the mainstream of Judaism, the only place they could really talk together was in their own little groups of fellowship. They would have their meals together, and Les illustrates how sharing a meal in a home moves a relationship beyond casual acquaintance into truly knowing someone and their family.