The first instance in Acts of the “gathering” language is in Acts 1:15. Here is that verse in context:
In those days Peter stood up among the brothers (the company of persons was in all about 120) and said, “Brothers, the Scripture had to be fulfilled, which the Holy Spirit spoke beforehand by the mouth of David concerning Judas, who became a guide to those who arrested Jesus. For he was numbered among us and was allotted his share in this ministry.” (Now this man bought a field with the reward of his wickedness, and falling headlong he burst open in the middle and all his bowels gushed out. And it became known to all the inhabitants of Jerusalem, so that the field was called in their own language Akeldama, that is, Field of Blood.) “For it is written in the Book of Psalms, ‘May his camp become desolate, and let there be no one to dwell in it'; and ‘Let another take his office.’ So one of the men who have accompanied us during all the time that the Lord Jesus went in and out among us, beginning from the baptism of John until the day when he was taken up from us – one of these men must become with us a witness to his resurrection.” And they put forward two, Joseph called Barsabbas, who was also called Justus, and Matthias. And they prayed and said, “You, Lord, who know the hearts of all, show which one of these two you have chosen to take the place in this ministry and apostleship from which Judas turned aside to go to his own place.” And they cast lots for them, and the lot fell on Matthias, and he was numbered with the eleven apostles. (Acts 1:15-26 ESV)
In Acts 1:15, we find the Greek phrase “á¼Ï€á½¶ Ï„á½¸ Î±á½Ï„á½¸” (epi to auto) which is generally translated “in the same place.” (In the ESV this phrase is combined with the phrase “the multitude of nouns” and translated as “the company of persons.”)
Now, some may wonder why I’ve included this passage in my study of church meetings, since the Holy Spirit did not descend on the believers until the day of Pentecost. However, several authors have suggested that the birth of the church is not found at Pentecost but in the earthly ministry of Jesus. (For example, see my posts “The Birth of the Church Demonstrates its Purpose” and “Proclaim, Teach, Serve.”)
This passage in particular demonstrates that those who followed Jesus recognized that they were a continuation of the people of God, not a completely new people of God. They were a new remnant, so to speak. In order to continue their identity as the new kingdom of God, they needed a twelfth person.
We do not learn much about church meetings from this passage. We do learn that others (besides the original twelve) had been with Jesus since the time of his baptism through his earthly ministry, death, burial, and resurrection. While we know that there were 120 believers together on the day of Pentecost, we don’t know exactly how many of them had been with Jesus from the start, but there were at least the original eleven (the Twelve minus Judas Iscariot) plus Joseph (also called Barsabbas and Justus) and Matthias.
We also see that they recognized that they had a part to play in decision making when they met together. The people who were gathered together came up with some principles and chose two men who met their criteria. There doesn’t seem to be any scriptural mandate for choosing someone who had been with Jesus since his baptism. Instead, they chose criteria that seemed proper to them.
Finally, while they recognized their own part to play, they also recognized and trusted the sovereignty and authority of God to make decisions. This is primarily demonstrated through casting lots. Casting lots is an Old Testament practice used to allow God to make a choice. (For example, see Leviticus 16:8, Joshua 18:6, 1 Samuel 14:42.)
So, while Peter spoke to the group and suggested that the group choose someone to take Judas’ place, the entire group worked together to choose two people, then cast lots to demonstrate their dependence on God and his authority and sovereignty.