We are firmly convinced that the Bible is God's Word. It doesn't merely contain God's Word. It doesn't become God's Word. It IS His Word. The whole Bible is inspired by God, through human agents, "to reveal himself and declare His will unto His church" (Westminster Confession of Faith 1.1).
As Paul writes to Timothy, "All scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work."
Our practice of preaching through books of the Bible is actually grounded in these biblical truths. We don't come on Sunday to hear what's been gnawing at the preacher throughout the previous week, or what's filled up his Twitter feed. We come to hear God. The practice of preaching lectio continua, consecutively through books of the Bible, recovered by the Reformers, at the very least guards the congregation against the preacher's soapbox.
And this brings me to the reason for this brief article, because this practice also relieves the preacher from having to figure out what to preach each and every week; we all know that we're just moving on to the next chapter.
And this next chapter, Genesis 34, has some, um, er, uh, well, just read it for yourself.