"God is just the people you love," I heard a doctor say this weekend. I was guessing she was Hindu, a religion that does not actively seek to expand or convert others and is still one of the world's largest mainly, I read, due to population growth. She was affable and unphased and even cracked anthrax jokes with chirpy paramedics while my sick friend was puking herself a shade off-beetroot. God bless the NHS.

Blood is a fundamental, and fundamentals are worth re-evaluating at times. I'm A Rh + myself, common as muck and a good thing too. I've given blood and received it, watched it shed and spilt. I've gone numb through gory bits on videotapes and disposed of sanitary towels, thinking - an abnormally high percentage of rapists find the thought of menstruation disgusting, which begs one to ask if whipping out a fistful of Always Ultra would be safer backstreet defence than a can of Mace - and wondering how much blood my father, an afore-mentioned paramedic, mopped up in his time. I scarred a drummers chest with a razor once, at his bewildering request. And glazed over as a motor cyclist ricocheted off a lamppost, said goodbye to his left leg and went careering into a wall. And walked over to him through a haze of leather and metal frictioned into smog, running petrol and blood.

And whether it's stains over the streets of Belfast, or cutting myself shaving, I have always wondered just how much there is in blood. Not in terms of molecular genetics, biophysics and Genome projects but in terms of family and extended family and race and faith.

There is no evidence that race exists. If one travels across this globe by land one will notice skin tones and physiologies vary by degree. If Charlotte Church bunked into a Wu Tang Clan photoshoot she'd be rumbled by even the most casual of fans but that does not imply the existence of two races, or three. However many one is supposed to accept exist. Race is socially more trouble than it's worth and scientifically bankrupt. Dependent on which criteria one uses any number of groupings may appear. Using lactose tolerance to group ourselves, for example, will result in north western Europeans, certain east African groups and Sari Indians falling into the same race, and everyone else into another.

Race is relativism and the continuing sense for race comes from a defensive/offensive reaction. Even embracing race as an immutable social concept seems determined to end in racism. We are one breed separated only by faiths (often mutated by diaspora, turned on the pivot-table of seeing oneself through the eyes of a dominant culture and restressing one's faith accordingly), sensibilities and a look. I once was surprised when Spike Lee said he didn't find "white girls" attractive, and still am when I meet, for example, girls who don't go for oriental guys. I shouldn't be. One has to conclude that this not an indication that human aesthetics betray any kind of deepset racism, but that our personal responses to physiognomies can sometimes be grouped at a broader level.

Metaforces and status, as far as I can see, are nowhere yet discovered in the blood. But the re-examining of any group who insists on their own exclusivity through any variant of lineage (blood, with all it's theatre really shouldn't be used as a catch-all for lineage) must be done with care. Invariably this tradition is tribal in origin. Land, property and title are passed from a father to his sons. Where no sons are had, the daughters of that family inherit but are forbidden to marry outside the tribe. Whether this is the roots of Jewish matrineal descendency is impossible to say.

Any sort of swinging, post-modern approach to faith may be fine until one wishes to join an exclusive group (I've met Turks in Berlin's Kreutzberg who are not recognised as German despite living there for generations) or are confronted by an aggressor who has a far more austere approach. Islam, a religion which has a history of military conquest leading to forced conversion to almost rival Christianity, has also gained followers in groups (in Indonesia, Africa and recently amongst Afro-Americans) who see it as resistance to oppression with roots in Judaeo Christianity.

It's a good thing that so much of the world now sees the lack of humanity on show in Taliban Afghanistan. And when you or I might be targets, despite our personal beliefs, I'd all for prevention. My personal belief is that I could maintain my independence, sit down fairly and squarely with a Taliban, ask to hear his side of the story, listen to it with no preconceptions and probably still despise him. But so often the end of a war is about negotiation, not resolution. Politics. And many lowly Afghans will get it, despite their own personal beliefs.

Faith, spiritual or societal, is not in the blood but interpolated, carved to our baseboard at childhood. When global panic stations are called, or something domestic goes deeply wrong, we find faith in a model of behavior guaranteed to place us somewhere recognisable. Sikhs turn to Sikhism, Zoroastrians to Zoroastrianism. To my shame I uncork something special, listen to Johnny Cash and write.

The first real blood I ever saw was in a book in a garden shed at the end of the 1970s. My friend Karl said he wanted to show me something but that I would first have to promise never to tell anyone. I agreed and he fished about in a box on a high shelf and produced some adult magazines. We flicked through these and he then asked if I would like to see something scary. He goes back into the box and hands me a book called "Ulster: The Facts." Produced for a Republican-sympathetic America, at the height of the IRA bombing campaigns, this book was counter-propoganda from a Unionist perspective. After a preface explaining Ulster's contribution to America in terms of the parents of various Presidents, there followed a glossy full-colour snuff magazine, centrefold atrocity shots, people opened out and cooked like meat, in their own brown black blood.

What do you do when people hate you? What did I do one night on Belfast's Sandy Row when a group of kids asked me aggressively whether I was Protestant or Catholic? I considered running, tried to map which end of the street I was on and offer the most beneficial answer but knew this was a gamble and, quite importantly, a lie. I considered explaining agnosticism and apathetic secularism and muttering that I wished to take no side but inside my head I heard the phrase whispered to those offering up their neutrality during the French revolution, with their backs against the wall and a sword to their throats, "And that is why we hate you."

The tribal and the blood are still with us for the psychological monkey buttons they push. Their heady symbolism remains the most skillful way superpowers that be have at distracting any blue collar energies that could be volumetrically troublesome. Fight the power, wherever that may be, not because you would like a personal access to an exclusive club but because the welfare of other people's kids should be as important to you as your own.

If we were to start the world afresh tomorrow, knowing what we know as articulate, learned street beings, only a bug-eyed lunatic would put forward the suggestion that royalty, aristocracy or anything but communal land ownership would be the fairest and strongest basis on which to build a future. Yet, we continue to accept and support the institutions that prevent any grass roots revitalisation of society from occurring on the basis of the historical, the God-granted, a line.

I sat with my friend in curtained off booth waiting for a doctor wondering why the hell the NHS were prescribing God. But thanking someone somewhere for the NHS.