I need from you Scriptural support that sex is a "wonderful gift from God". I can't recall anything that would suggest such a thing. I've explained in detail at my blog that sex is a specific biological function, that it contains a pleasurable element that guarantees that it gets done for the survival of our species. It is man who has elevated sex to some lofty position due to man's desire for self-gratification.
It has been a while, but I have finally deigned to respond to this query. Wedged between Ecclesiastes and Isaiah sits The Song of Songs. In eight chapters, a poetic dialogue, with a non-Greek chorus, a man and a woman state their love for one another in frank, carnal, sexual terms. Reveling in the simple joys of each others physical forms, the poem is a celebration of sexual love at its most basic. The power of the poem's climax, in chapter 8, is such that verses 6 and 7 were the verses I chose to use at my wedding:
Wear me as a seal over your heart,
as a seal upon your arm;
for love is strong as death,
passion cruel as the grave;
it blazes up like a burning fire,
fiercer than any flame.
Many waters cannot quench love,
no flood can sweep it away;
if someone were to offer for love
all the wealth in his house,
it would be laughed to scorn.(REB)
Until the Protestant Reformation, no other Biblical book was as commented upon, as lavishly praised, or studied as much as the Song of Songs. While it was often interpreted as an allegory for the Divine desire for a relationship with human beings, and the intensity of the sexual longing being a symbol for just how deep is God's desire to be in relationship with us, I was admonished once not to dismiss the earthiness of the book's language so easily.
How beautiful you are, my dearest, how beautiful!
Your eyes are doves behind your veil,
your hair like a flock of goats streaming down Mount Gilead.
Your teeth are like a flock of ewes newly shorn,
freshly come up from the dipping;
all of them have twins, and none has lost a lamp.
Your lipe are like a scarlet thread,
and your outh is lovely;
your parted lipe behind your veil
are like a pomegranate cut open.
Your neck is like David's tower,
which is builtwith encircling course;
a thousand bucklers hang upon it,
and all are warrior's shields.
Your two breasts are like two fawns,
twin fawns of a gazelle
grazing among the lilies.
While the day is cool
and the shadows are dispersing,
I shall take myself to the mountains of myrrh
and to the hill of frankincense.
You are beautiful, my dearest,
beautiful without a flaw.(Song of Songs 4:1-7, REB)
The earthiness is not just in the metaphors the lover uses to describe his beloved (pomegranates, sheep, gazelles) but most especially in the end where he speaks euphemistically of "the mountains of myrrh"; he is speaking here of her mons and the beauty thereof, in terms of intoxicating perfume.
While it isn't the Kama Sutra, or The Art of Love (better titled The Art of Seduction), it is among the more passionate, and even explicit at times, love poems ever written. It takes away that power to treat it as a metaphor.
Its inclusion in the Biblical canon is often put down to the possibility that it was part of wedding liturgies. Yet, one has to wonder, considering the erotic nature of the poem, what kind of wedding would include a description of her husband's thighs by his bride as "pillars of marble", and the "aspect" (his penis) "like Lebanon, noble as cedars". I certainly don't want my girls talking about their grooms that way on their wedding days!
No, I believe it is included for the simple reason that this is a celebration of part of God's creation, indeed the part that God called "very good" at the end of day 6 - human beings. Human beings, among our many traits, are sexual creatures, who revel in the physical pleasures our bodies accord. Since there is no history to guide us, nor any textual evidence linking the poem to weddings or marriage, I believe that we should accept them for what they are - a powerful, erotic celebration of human sexuality as a divine gift.
I hope that answers some questions.