Birds do it . . . bees do it. And happily, humans too.
Our faith is earthy in the right sense of the world. We are grounded, creatures of dust. The hope of the Gospel is Creation renewed - New Creation! not creation forever eradicated.
It's not more spiritual to not be concerned with stuff, with all the bits and pieces of creation, including our sexual identity and expression. It's an ancient heresy (Gnosticism - which plagues the Church and Christian thinking to this day) that we would be more spiritual if we were less earthy, more ethereal, more Heavenly-minded. From the Creator's perspective (Who, after all, made sexual beauty and bounty), it's not body evil; spirit good.
God's good gifts of creation include sexual intercourse and all other aspects of our sexuality - who we are as male and female, sexual beings. Like many things of creation, we have gotten it wrong, messed it up, done it wrongly. No wonder that sexuality, being so linked to newness, new creation, new birth, to the genesis of good things in a broken world - that this should be the very area that should know the experience of so much temptation, failure - morally-, physically- and spiritually-broken lives; so much betrayal and loss.
But the key gift of sex is a sacrament, say our Catholic friends. Deep inner things, God things, are expressed in the physical, temporal and obvious acts of such expression. The friendship and love expressed in sexual intimacy remains a gift of common grace, of God's grace to all his creatures. Pleasures abound still, thank God, in His world.
In originally unspoiled Creation God's choice appears to be that sexual intimacy and bonding at this most intimate level be gift for a man and a woman; it's how Jesus described marriage. Clearly, in Old Testament passages describing the relationships of God's ancient people Israel, there are other examples, incuding polygamy and the sometimes abundance of concubines (in patriarchial not matriarchal expression and perhaps even in bias). The results are not aways pretty - but there it is. Today there is an ongoing struggle, as Jesus' followers seek to understand Scriptural dictates and demands without being pharisaical and in fact more like Jesus - Scripture, which I take as authoritative and inspired (but our interpretations of it not necessarily so). And what is to be seen and applied as descriptive (i.e. the way it was) versus what is prescriptive (the way it should have been then). And even with the latter, the question remains: Yes prescriptive for them, then and there; but does that still hold for us today, in every context and culture?
In Christ, says St. Paul, there's no longer male nor female, slave or free, Jew or Gentile. We know however that on the ground such categories continue. But there have been new and maturing attitudes and interpretations that have moved nations to, for the most part, outlaw slavery in the civilized world (thought there's so much work still to be done in combating racism and freeing slaves, say, in parts of Africa. And the first century world saw the increasing break-down of barriers (at least, in the early Church) between Jews and Gentiles; pity that hasn't continued. And, not too long ago in our own times has come the increasing freedom and elevation of women and women's concerns (though there's still much work to be done).
Jesus said that in God's coming Kingdom, men and women will not be given in marriage at all but will be like the angels; which I assume means without sex or becoming somehow sexually neutral. This is kind of a bummer when first heard. One wonders what else that we now so pleasurably embrace will no longer be part of human flourishing and existence - and will we know and remember, and really, really miss it? Or will the new pleasures of the New Creation be such that we'll laugh at the idea that we even thought of such previous pleasures as we now know and experience them as worthwhile, and worth chasing after. Nontheless today, we get it wrong when we fail to see and utilize our sexuality as the good gift it is of our Creator, when we exploit and abuse it in ourselves and others; when we think it's just for producing babies and not also intended for pleasure.
Scripture has much to say about sexuality, about the knowing ('and Adam knew his wife and she conceived . . .') that is as intimate as the ways in which God knows us: at heart, with mind - and also with our bodies. (You only have I known of all the nations . . . , God said to Israel of old, God's ancient People - using the same word, which bespeaks a close-linked intimacy.) Those He foreknew, He also called . . .
There is spiritual and physical ecstasy in knowing God, the saints have revealed - an experience that is similar and that rivals, and is very like sexual intimacy at its best. The body is in rapture through the one; the soul by the Other.
'Thanks be to God for His unspeakable gifts.' That is: they can scarcely be put to words. They are over-the-top, miraculous and immense - pleasurable beyond all tellingl They are, each one, worth pursuing and sharing. But in epressing true love of God and others, the sharing must be shaped by the channeling restraints and release of God's goodness, God's intent.