Sometimes the church of Jesus Christ has periods of persecution and at other times it has periods of popularity. In Acts 9 a period of opposition comes to an end with the conversion of Saul of Tarsus and a period of popularity begins. We can see the popularity described in verses 35 and 42. One feature that marked the period of popularity was spiritual power and I would suggest that is what Luke is stressing in these verses.
Luke gives a beautiful description of the spiritual environment in which Peter laboured for Jesus in verse 31. He says that the church was healthy (it was being built up and growing in stature as well as in numbers). Two details are highlighted: they walked in the fear of God and they enjoyed the comfort of the Holy Spirit.
It is obvious from Luke's description that true fear of God does not produce inactivity. Usually it is fear of man that brings inactivity into a church. The fear that Peter is describing is not terror but reverence, and reverence includes obedience and service as well as adoration.
The church was walking in the ways that pleased the Lord and therefore he gave to them the comfort of the Holy Spirit. This is a reference to all the good things that the Spirit brings into the lives of those who trust in the Lord. The particular kind of comfort will be connected to its specific situation and we can see examples of it in the incidents that Luke narrates. Sometimes, the Spirit gives peace and joy, at other times he gives assurance, at yet other occasions he gives consolation by reminding his people of God's promises. It should be our desire and our aim to have this kind of dedication (walking in the fear of the Lord) and this kind of spiritual enjoyment (the comfort of the Holy Spirit).