All human life is sacred, a wonderful gift of God. So we care for each person as well as we possibly can, doing our very best to make their lives as full of opportunity and as free of pain as we're able. But in that sentence there are already caveats – it's full of "ifs" and "buts". What happens when resources don't stretch as far as we'd like and we can't educate or heal or care for everyone as these children of God need or deserve?

It's a quandary, and one that's sharpened when we're confronted by people who don't seem to respond to anything we can do for them at all. There are people in a "persistent" or "permanent vegetative state" (PVS), exhibiting no trace of higher brain function. Is it ethical to withdraw nourishment from them and allow them to die? Trial cases were fought in the US over Terry Schiavo and in the UK over Tony Bland, brain-damaged at Hillsborough. They are hard, hard questions.

The case of people with so-called "locked-in syndrome" is different. Their bodies don't work, except often their eyes, but their mental faculties are still operant.

Now, though, an extraordinary experiment has found a way of helping them to communicate by using a brain-computer interface to "read" their thoughts and let them answer basic yes or no questions. The study by Switzerland's Wyss Center was on four patients with advanced amyotrophic lateral sclerosis whose disability was so profound they could not even move their eyes. It used changes in blood oxygen levels to interpret the answers to questions, with an accuracy of around 75 per cent. One patient repeatedly told researchers he didn't want his daughter to marry her boyfriend (though she did anyway – "nothing can come between love", said Prof Ujwal Chaudhary).

For those affected by conditions like this it's a remarkable advance. But what's even more remarkable is that in spite of the severe limitations of their lives – they all rely on artificial ventilation to survive – the patients all reported being happy most of the time.

There's much to ponder in this. As Christians, we might want to think of three things in particular.

1. First, it underscores the value of human life in the face of what's been described as a growing culture of death. Moves to legalise assisted suicide in the UK have been fiercely resisted by evangelicals and Roman Catholics, so far successfully. Euthanasia, legal in several countries, is a step further still. Reports that a dementia patient in Holland who had previously expressed a wish to be euthanised had said "I don't want to die" and fought back when a doctor tried to inject her are a terrible example of what such a culture can lead to.

When people are are conscious and alert in spite of being totally immobile, it ought to be unthinkable that anyone would seriously propose terminating their life support without their consent. But nothing can be taken for granted, and at the very least this research reminds us again of the respect we owe to those who are entirely helpless.

2. Second, it warns us not to assume we can prejudge the quality of someone else's life with any sort of accuracy. A frequent refrain in debates about euthanasia and assisted dying, when someone's unbearable suffering is advanced as a reason for ending their life, is: "You wouldn't treat an animal like that." But that's the point: human beings are not animals. We are mammals who share an evolutionary space with other mammals, but Christians believe we are fundamentally different because we have been given the opportunity of a freely chosen relationship with God. We cannot assume that life is not worth living for someone because it's not the life we, or they, would choose.

3. It throws a light on the huge resources developed countries are prepared to make available to maintain life when they believe it's necessary. The Swiss research is very important, but directly important for a tiny number of people who are kept alive by advanced modern technology. It is absolutely right that they should be, but as an ethical question this is quite niche. Far more urgent in most of the world are issues around vaccination, maternal mortality, malaria and HIV – not to mention the neglected tropical diseases that kill and disable millions every year. The campaigning energy devoted to questions around euthanasia and assisted dying isn't misdirected, but campaigners need to see these as equally grave moral scandals.

It is not possible to say that life should be preserved as long as possible in any and all circumstances, no matter what its quality. Some Christians would say so, but many more would simply have serious fears about the effects on society of a system that allowed or encouraged people to opt for death when they could choose life. The research on locked in syndrome patients might at least encourage people to focus more on life and less on death – even in the most challenging of situations.

Follow Mark Woods on Twitter: @RevMarkWoods