"I've been in church for over 30 years and as I was flipping through my Bible I realized I haven't heard a single sermon from the Song of Songs [known also as the Song of Solomon]. I suspect there may be many books and passages I've not been introduced to either. Why?"
Let me begin with a personal story. When I was in undergraduate school, I was the pastor of a small Methodist church in Florida. I asked the congregation what book they wanted me to cover in an upcoming sermon series and overwhelmingly they chose the Song of Songs. Things went fine the first two weeks, but as I studied the text for the third I realized there was NO WAY I was going to preach on that text, and frankly, I felt pretty uncomfortable even reading it aloud.
Why? Because the text was erotically sexual and I believed it had no place in my pulpit even if it was in the Bible. The passage in question described the physical attributes of the woman lover and the description in chapter three would be rated G when compared to the description in chapter seven!
You see, it seems there are certain themes and concepts in the Bible that "Christians" get pretty uncomfortable with and sensuality/sexuality is one of them.
The problem is, there are many passages that press our discomfort zone, and so the "wise" preacher stays away from them regardless that they are good and valid portions of the Bible. The notion of offending the church's sensibilities often becomes more important than truth.
And the truth is, the Bible contains a number of themes/passages that run counter to "puritan" Christianity. Indeed, this even causes translation difficulties, for often the original languages of scripture are rather course, and on several occasions quite crude. So to "save us" from being offended, translators in nearly every case have modified or tempered the language to preserve sensibilities. However, in so doing we have lost the flavor, and often the meaning, of the particular passages. Further, these passages have been generally avoided by pastors and educators so we are unprepared for what lies behind many of these passages.
For instance, most of us would be shocked to read Psalm 109. In this hymn the psalmist is so angry with someone that he prays a number of curses upon them curses like death, impotence, loss of all property, and lack of pity for the whole family. And he does so in a mean-hearted spirit! In Judges 3 the assassination of Eglon while in the restroom and the rather vivid description of his death would cause no little distress if read on Sunday morning. And translators are unable to print the actual cat calls of Rabshakeh recorded in 2nd Kings 18.27 because of the crude language. These are but a very few of the many passages that would offend the average "Christian." At least, that's what most ministers and translators believe.
And my experience has borne this out. Most of the time I have discovered my congregations would rather hear "nice" passages and avoid any conflictual or uncomfortable texts because, "We don't want to know about that stuff."
The Song of Songs is a beautiful love poem but it is erotic. To get around the obvious content the church has historically either avoided it or else chosen to interpret it metaphorically (it must be symbolic it couldn't really be a lover's poem; that would be unpuritan!). That's why our writer hasn't heard many (any) sermons on it. And as long as ministers and translators "protect" their congregations and readers, the church will continue to be ignorant of many passages and even whole chapters and books of the Bible.