A sixth dimension of the early community of faith were the signs and wonders that the apostles performed (2:43). This was a direct consequence of the fact that they had received the Holy Spirit. It is no coincidence that the chapter immediately after Pentecost is about the healing of a lame man.
Peter and John are at the temple to pray, and a lame man looks at them expectantly. They have something better to offer than money. They see him and say, "Silver or gold I do not have, but what I do have I give you" (3:6). They then help him up, and he is able to walk again.
It is sometimes pointed out that, today, we as a church often have the silver or gold, but we don't have the power to say, "In the name of Jesus Christ of Nazareth, walk." Obviously if we had to choose, the latter is more important. When we are comfortable, we often do not feel the need to rely on God, even though in reality we need him just as much as ever.
Some believe that God sometimes pushes back on us when we get too comfortable and forget that he is the center of things. Whether he is so active in getting our attention or whether reality itself has a way of reminding us, life often does pull the rug out from under our feet. The problem with a life of ease is that you take things for granted. You become unthankful. Perhaps this is partly why "it is easier for a camel to go through the eye of a needle than for someone who is rich to enter the kingdom of God" (Matt. 19:24).
The healing of the lame man leads naturally to a seventh feature of the earliest Christian community. The miracle brought the opportunity for witness, "evangelism," with the result that others join the community destined for salvation when Christ returns (cf. Acts 17:31). On the one hand, the picture we get of the early Jerusalem believers is that God largely brought the opportunities to witness to them. They didn't go knocking door to door in Jerusalem. They didn't stand at the temple door passing out tracks.
They saw a lame beggar and healed him--then plenty of people wanted to hear what they had to say. They were praying and filled with the Holy Spirit and began to speak miraculously in other languages--and plenty of people wanted to hear what they had to say. It is not the only model for sharing the good news that Jesus is risen from the dead, but it seems to have been the way it happened the most at first.
And people respected them. They were "enjoying the favor of all the people" (2:47). It would not always be that way, to be sure. Very quickly they came on the radar of the leaders of Jerusalem too. But when you are doing good in the world, people notice you. Fair-minded people respect you. The early church did not get people saved and then help them. The earliest believers helped people, and people got saved.
The miracles of the apostles--as well as the trouble they got into--gave them the opportunity to give witness to Jesus' resurrection. After they have healed the lame man, Peter gives the second sermon in Acts. Its basic content is similar to the Pentecost sermon.
The people of Jerusalem, Peter charges, put Jesus to death, "the Holy and Righteous One" (3:14). They ironically put to death the "author of life" (3:15). Then comes the key line in almost all the sermons of Acts: "But God raised him from the dead." It is faith in Jesus that healed the man, faith in the one God raised, faith that God is a God who brings life from the dead.
And Jesus' death was all part of God's plan. When we read the Law and the Prophets with spiritual eyes, we can see all sorts of hints we didn't see before. For example, Jesus is a prophet like Moses, just like Deuteronomy 18 talked about.
The bottom line? Just as in the Pentecost sermon, the appropriate response is for Israelites to repent of their sins and turn from their wicked ways (3:26). Jesus is in heaven, waiting to return to refresh the earth (3:21) and he wants them to be a part of his kingdom.