During advent at Emmanuel we're going to be following the readings in the Revised Common Lectionary. This will doubtless feel odd at times, both because anything new can feel a little strange, and also because there are some obvious problems with following the lectionary (at least, there would be if you did it all the time). For example:
1. The readings are frequently very short - too short to get any sense of the context.
2. The first problem is exacerbated by the fact that the readings often miss off significant portions at the beginning and end (or even sometimes, in some lectionaries, the middle) of the passages being read, which are necessary to make sense of them.
3. Many parts of the Bible are not included at all (at least in the readings for Sundays), with the result that they disappear entirely from the corporate church's worship. This really would be a serious problem if (as many lectionary fans wish) the whole church throughout the world adopted the same lectionary.
4. The logic and coherence of sequential exposition of contiguous passages in a single book is lost. (FWIW, I think that many preachers tend to overestimate the value of sequential exposition in this respect - try asking a member of your congregation next Sunday what you preached on last Sunday, and you'll discover why. yet I think there is still something to be said for the point.)
5. The familiar passages that (understandably) dominate lectionaries tend to become over-familiar, leading to a stereotyped picture of the Christian faith which loses the surprise-factor of the unfamiliar parts of the Bible. (I mean, how many lectionaries devote substantial attention to large portions of the book of Judges?)
6. Related to the previous point, I'm afraid I wonder how many of the choices of readings in some lectionaries are dictated by theological prejudice against unpopular or controversial aspects of the Christian faith. Imprecatory Psalms are either ignored entirely or heavily edited; large portions of Leviticus, Joshua, Judges and the prophets fail to make an appearance; you get the picture.
7. The choice of readings for particular seasons of the church year may at times reflect exegetical misunderstandings about the texts being read. Even if these misunderstandings were not present in the minds of the editors, they could easily be reinforced in the minds of congregations. For example, if the season of Advent is broadly about the anticipation of Jesus' final return in glory, then the inclusion of Lk 21:25-36 is likely to reinforced the widely-held but (to my mind) mistaken reading of the Olivet Discourse as a prediction of this great event, rather than a prediction of the destruction of the Temple in AD70.
Having said all that, to use the lectionary at least some of the time promises some significant blessings. Consider the obvious advantages of the lectionary:
1. It's a significant liturgical expression of unity with the church throughout the world.
2. It gives significant variety to the readings by including lots of different biblical texts in a short space of time.
3. It sheds light on the historic significance of the different seasons of the church year.
4. It has the potential to shed light on the meaning and significance of different parts of Scripture by encouraging us to juxtapose different texts that might not normally be associated with one another.
It seems to me that this final advantage is crucial for preachers wanting to get the most out of the lectionary. We need to assume for the sake of argument (and charity) that the people who compiled the lectionary knew their Bibles really well. Then we simply ask ourselves not just "What do these passage mean?" but also "What light to these passages shed on one another?"
To put it another way, we might ask, "Why would someone think that Jeremiah 33:14-16 has anything to do with 1 Thessalonians 3:9-13 and Luke 21:25-36?"
The key then is not merely to let all three passages speak at the same time, but also to let the compilation of the lectionary itself act as an interpretive guide, or at least as an interpretive pointer. And since everything in God's word has something to do with everything else, you'll always have something to say.