The sad story of 23-year- old Dan James' paralysis on the rugby pitch and his subsequent choice of an assisted suicide at the Dignitas clinic in Zurich, to escape what he deemed a "second-class existence", has troubled me. Not because I feel anything but great sympathy and admiration for him and his family – and I know from first-hand experience the tortuous debates they would have had together in the months before his final journey to Switzerland – but because it opens an ethical debate which we are ill-prepared to address as a society.

My own ethical journey on the subject started when my mother, Dr Anne Turner, was diagnosed with Progressive Supranuclear Palsy, a particularly unpleasant degenerative neurological disease which could have left her completely paralysed and unable to communicate. Despite our every entreaty, she was determined to have – and had – an assisted death at Dignitas nearly three years ago. My two sisters and I went through denial, despair and eventual acceptance. We came to realise that our mother's happiness, autonomy, and fulfilment were more important to us than having her alive. When we consented, she became a happy person again for the last two months of her life.

The reaction of virtually everyone to Dan James' case has been sympathy and respect for Dan's rights as an individual. Yet at the same time the case breaks new ground. The vast majority of the population wants assisted dying for the terminally ill to be legalised. But Dan wasn't terminally ill. He was a young, paraplegic man, probably with several decades of life ahead of him; he hadn't started the process of dying. Assisted dying for him was really assisted suicide.

The opponents of assisted dying for the terminally ill will trumpet Dan's case as evidence that assisted dying inevitably leads to assisted suicide on demand for anyone who doesn't want to live, or for those whom society can't be bothered to keep. Several studies have shown that properly regulated, legalising assisted dying does not lead to any of these abuses, in fact, the opposite – it gives vulnerable people greater security. The best outcome for patients is to be able to discuss all their wishes with doctors openly.

Palliative care doctors have very legitimate concerns about the introduction of assisted dying legislation and we need to engage in an open debate with them. But if they are joined at the hip with religion, it becomes impossible to separate their genuine concerns from religious spin.

This dishonesty is at risk of polarising the debate on end-of-life issues. I'm not remotely anti-religion (and, as it happens, most people of faith support the legalisation of assisted dying). But they must recognise that, when assisted dying is legalised, the religious will still be able to exercise the same moral choices they can today.

Although I am an advocate of assisted dying for the terminally ill, I don't like the idea of a mentally competent 18-year-old being able to buy an over-the-counter suicide pill. Dan's case falls uncomfortably between these two points. But to me, life does have value. And I would like to have an honest debate with people of faith, as well as humanists and atheists, as to how to balance the rights of the individual with the need to value life itself.

I'd like religious opponents to let go of their desire to control other people's lives, and to make sure they "declare their interest" when arguing these points. The ethical debate needs religion, honestly. Please will those of faith take part in a grown-up debate about giving patients real choice at the end of their lives?

Edward Turner is a trustee of Dignity in Dying