Like most superlatives, the word 'phenomenon' is handed out far too cheaply these days. But in the case of the Serial podcast, the audio documentary series which arrived out of nowhere at the end of last year, it is fully deserved.

Sarah Koenig's riveting week-by-week unpacking of a dubiously-resolved murder case gripped millions of people who'd previously never heard of Koenig, or her complex subject Adnan Syed. So great was the buzz around the show, it reached no.1 on the iTunes charts before it was even released, and went on to break every podcast record in the format's limited history. In fact, it revived mainstream interest in the whole idea of podcasting, which had slowly been flagging up to that point.

While the first season surprised everyone, there were serious concerns about how Koenig could follow it. In Syed's case, she'd managed to find one of the most intriguing stories imaginable, with all sorts of loose ends and complex characters; a perfect fit for the multi-angle dissection around which Serial is built. Could she find another? This time, she'd no longer be an under-the-radar public radio broadcaster (there's even a Hollywood movie in production about her), and her interview subjects would be well aware they were part of an international media sensation. Would people really talk to her as candidly as before? And could an audience be persuaded to stick with another long-form story?

Those questions have been answered, at least in part, by the arrival of season 2 at the end of last week. One thing's for sure: the audience is still very much engaged. In fact, the sheer numbers trying to download the first episode caused the Serial website to crash within 30 minutes of release.

Once listeners did manage to get hold of the episode, they found themselves plunged into the heart of a brand new story which, from the evidence of that first 45-minute insight, looks every bit as compelling as the case of Adnan Syed.

This time Koenig has picked up the tale of Pt Bowe Bergdahl, a soldier who voluntarily walked off his base in Afghanistan and straight into the hands of the Taliban, who held him in mainly solitary confinement for five years. The central tension: is Bergdahl a heroic whistleblower, whose efforts to draw attention to leadership failures above him went badly wrong, or is he just a deserter? If Koenig can manage to recapture the magic of season 1, we'll be flitting between those two positions for the next few months.

The first season of Serial didn't touch on religion much (past the moderate Islamic faith of its subject), and it's unclear whether the second will 'do God' either. There's an odd reference in the first episode to how Pt Bergdahl talks to the Hollywood film-maker who picked up his story about 'the existence of God', but that may be a red herring. Still, I think there's a lot for Christians to be interested and engaged in about Serial, and particularly its phenomenal success.

Bergdahl comes from a strong Christian family. In fact, his family's former pastor was the subject of a 2014 Christianity Today interview, at a time when the story of Bergdahl's release from captivity was receiving signifiant media attention in the US. Before his capture, Bergdahl did not make what the pastor calls a "public profession of faith", as they had been "working through this questioning period together... whether he ever got to the place of saying, 'Yes, this is my commitment,' I don't know."

However he continues with a piece of information which Koenig may well pick up on as the story unfolds: "While [Bergdahl] was in captivity, he made a point of celebrating Christmas and Easter, and asked his captors to join in with him in celebrating, and I find that profoundly significant." Did Bergdahl find God in solitary, or did he just find the rhythms of the Christian calendar a small way of staying connected with home? We're likely to find out in the weeks ahead.

People are thirsty for great story, well told. More interesting is the way that Serial has captured the imagination of so many millions of people. In an undeniably visual age, full of distraction and multi-tasking, Serial has convinced millions of people to put down everything and listen – concentrate even – to a single story. The reason: Koenig has managed to find a format and a story so compelling, so universally relevant, that we actually want to fight those urges to do several things at once and give her our full attention.

Since Christianity is meant to be spread, and since that spreading all orientates around a story, this should be interesting to us. Could we find ways to tell the story of Jesus which get people hooked, turning off all other distractions to hear a little more every week? Historically, the Church has been good at this. Perhaps it's helpful to ask: How would Sarah Koenig present your Sunday sermon? Or more creatively, how would Koenig tell the even more complex, compelling and primal story of Jesus?

Great storytelling can challenge (and possibly change) injustice. Perhaps the most surprising aspect of Serial's journey so far is the way that the story has leaked out of the confines of the documentary format and into real life. To the untrained listener, the murder conviction handed to Adnan Syed seemed shaky at best, and now new evidence found as part of the show's investigations has been enough to grant him an appeal. Bergdahl's apparent desertion – which led to a highly contested prisoner exchange – has made him a figure of derision in the US, but if Koenig manages to illuminate his motivations, it's possible that he could see himself recast as a hero. Whatever happens in both cases, there's a fascinating precedent being set here for the media shining a light on injustice and perhaps even resolving it.

A single episode in, the jury is still out on whether Serial's 'difficult second album' can repeat its unprecedented early success. The amazing cliff-hanger to the first part bodes well however, and if that manages to live up to the expectation it has now created, then millions of us are going to be glued to Pt Bergdahl's story for months to come.

Martin Saunders is a Contributing Editor for Christian Today and the Deputy CEO of Youthscape. You can follow him on Twitter: @martinsaunders