I have always been curious, and more than a bit distressed, that the Revised Common Lectionary uses so little of the Book of Acts in the 3 year cycle of readings for Sunday. I think I read somewhere (I think in a work by Methodist Bishop William Willimon), that the RCL only uses less than 20% of the Book of Acts in the entire 3-year cycle. I did not do the exact math, but as far as I can tell by looking at the index of the RCL, that appears to be about right.
I always wondered why that was exactly because the stories are phenomenonal. The themes of how the early church expanded are truly staggering and to the point in a Post-Modern/Post-Christendom/Post-Whatever Western world. In some ways, I think the problems that the Church in the West now faces from the larger, secular culture are not all that dissimilar to what the church faced in the 1st century. We don't have persecutions or such as that, but we do largely face a secular culture that does not know or understand Christianity, or at the very least makes ill-informed assumptions and assertions as to what Christianity is all about.
To that end, I have consistently wondered why the book of the Acts of the Apostles is so neglected in the Sunday readings. About the only time that Acts is read is during the Easter season (usually in lieu of an Old Testament gospel) when the emphasis is not on the themes of Acts but usually more on the Resurrected Christ. Much has been written about this in certain academic tomes, but I have yet to see much, if any, of this scholarship applied on a diocesan or parish level.
I have always wondered what the modern Church could learn by more forcefully engaging the stories and themes of Acts instead of usually them as occasional side stories in the Easter season.