Acts 2:41

Many of them believed. Those who believed, were baptized immediately! [Those who did not believe had no reason to be baptized.] About three thousand people. The Twelve could have done the baptising themselves. Chrysostom, assisted by the church elders, immersed 3,000 in one day in 404 A.D. There were plenty of deep pools in Jerusalem. Certainly the Seventy-two would be there, and perhaps others of the disciples. Group. Messianic community. The one church exists in a locality as a group.