Though a solemn chapter about a murderous king and his downfall, there are also comic elements here which help to expose the foolish arrogance of Herod through mockery (Ps 2:4,5). However, the chapter has other themes too, including an emphasis on angels which warrants further thought.
It may help to start by considering angels in general. The original word means ‘messenger’ and can be used of human beings (eg Lk 7:24). However, it often applies to non-human spirits from heavenly realms who become visible in our realm at certain important moments (eg Lk 1:19). In doing so it appears they are actually existing in both domains (heaven and earth) at once. This is seen, for example, with the ‘Angel of the Lord’ in the OT whose link to the Lord in heaven is so close that to hear him speak is to hear the Lord (eg Ge 16:7-13). The same concept can also be seen in reverse in passages where an earthly entity has an angel in heaven, such as with the churches of Revelation 2 & 3 (see Re 1:16, 20; cf Ep 2:6). And though it’s beyond our minds to grasp what all that means, thinking about it widens our view of reality as we see that our lives are intertwined with an unseen and glorious realm (see Ge 28:12-17). This is a humbling thought. We can imagine our lives as so big and significant, but an awareness of how creation is actually far greater than our little existences, helps us to tone down our self-obsession. And once we have been humbled, we are then ready to receive gracious glory from God since he has granted to us the privilege of being served by the realm of spirits, as his adopted sons through Christ (He 1:14).
But what about the angels in Acts – what are their particular roles in the book? Well, angels only appear in select places and those moments emphasise the changing nature of old Israel. Some in Israel thought of angels and their place in the nation’s history as so significant. Maybe they saw angels as their protectors (Ps 91:11) and the Lord’s army (2Ki 6:15-17). Certainly they valued them highly, as can be heard in Stephen’s references to them in his speech (Ac 7:53) and in Hebrews where the writer, in order to discourage Christian Jews from apostatising, starts his writing by noting that Jesus is far greater than any angel (He 1). Angels were valued in old Israel. But in Acts Luke tells stories of the angels going over to the side of the Christians. They: break the apostles out of prison and send them to the temple (Ac 5:19,20); direct Philip to the Ethiopian Eunuch (Ac 8:26); tell Gentile Cornelius to get in touch with Peter (Ac 10:4,5); and, in our chapter, release Peter before sending him away and bringing Herod to a sorry end. The conduct of the angels of Acts shows where God’s allegiances now lie. To Luke’s Jewish readers that acted as a warning to them about losing God (cf Ac 28:25-28). To Luke’s Christian readers that brings peace, knowing that they were (and we are) surrounded by armies of unimaginable power.
These thoughts link in with our verses. It was an angel who showed up Herod as feeble by freeing Peter and walking him out of the prison (v11). From there, Peter now makes his way to the house of Mary (v12), the mother of John Mark and a relative of Barnabus (Co 4:10). The house seems a large one and is hosting a prayer meeting. But when Peter calls at the gate, an amusing incident follows. The slave girl checking the gate (v13) recognises Peter’s voice but in her joy flees back inside without letting him in (v14)! The believers, however, do not accept her report, thinking either she is mad or has seen Peter’s ‘angel’ (v15), ie God has enabled Peter’s heavenly presence to appear whilst he himself is still in prison. But Peter is no angel! So he keeps knocking and, at last, they admit him and are stunned, as he recounts his thrilling tale about a real angel (v17).
But then Peter leaves the city (possibly for Rome). The church will now be pastored by James, Jesus’ brother. The time of the apostles is fading; their work lies elsewhere. And with their, and the angels’, departure, Jerusalem moves closer to the doom Jesus predicted for her (Lk 23:26-31). So it’s a bittersweet moment. An amazing rescue has taken place. But a city is dying. She has rejected Messiah & lost life. However, the heavenly Jerusalem will replace her (He 12:22-24).