Over the last half century there has been a consistent assault on Christian ethical values in the name of secular progress. The outcome has been almost uniformly disastrous in terms of social cohesion, personal wellbeing and the stability of society. The latest proposals to license assisted suicide continue the same pattern.

There is something almost touching about the naivety and optimism of progressives. If it wasn't for the fact that the naivety was lethal in its consequences.

This determined, over-optimistic self-reliance is either caused by an inability to read or recognise evil, or else the reason for it.

Adept at spotting the structures of social injustice, there is a failure to trace them back to the cause – the flawed human heart.

The reason this matters so much is that every attempt to improve society by attacking a perceived injustice leads to a greater problem, and in the recent past on a catastrophic scale.

As the momentum grows to change the law to allow and promote assisted suicide, and the arguments for and against are batted back and forth, it might be helpful to explore the recent history of what has happened on those occasions when Christian ethics have been repudiated.

The obvious place to start is abortion.

Beginning with a legitimate concern for mothers who were the victims of rape or whose mental stability might be threatened or impaired in any way, the law on abortion was modified and expanded. But there were some important safeguards designed to placate critics. The signature of two doctors was required, and the mother's physical or mental health had to be seriously endangered. Society was promised that this was a small-scale act of legislative and moral compassion which would be carefully monitored and strictly controlled.

In this country alone that has developed and degenerated drastically. Nine million deaths later, it has become abortion on demand and you cannot get employment in medicine if you have any reservations. Does this development and moral degradation constitute a deception of grotesque proportions or a catastrophic failure to understand human and political nature? Probably the latter.

The campaign to change our marriage laws has taken a similar trajectory. It started with the plea for social justice and clemency, and morphed into a weapon of social and economic exclusion against moral conservatives.

Its beginnings were the soft and insistent pleading for justice for a small proportion of same-sex attracted people. The National Office of Statistics placed the proportion of society at about 2%. The argument that followed proposed that as a matter of justice same-sex couples should have the benefit of legal protection when they set up home together and be given civil partnerships. As a matter of justice and fairness this seemed obvious. It was assumed that this would be it. Except that it wasn't.

The demand moved on to marriage. Whether the changes made to marriage law constitute unintended consequences or not, the consequences were more far reaching than the original arguments proposed. Because no one could find an adequate definition for adultery between two women, rather than confront the biological issues, the grounds of adultery for divorce were removed for straight people too. But this constituted an enormous shift in morals and in the significance of sexual fidelity between heterosexuals.

The beginnings of an industry in surrogate parenthood took off in order for same-sex attracted couples to provide themselves with children for whom one, but only one was the biological parent. No one gave any thought to the rights of children to have at least the possibility of accessing both their biological parents at the beginning of their life.

Catholic adoption agencies which had decades of experience in placing children for adoption were closed down overnight because their ethical outlook precluded placing children for adoption with same-sex couples. It was another example of vulnerable children paying the price for so-called equality legislation.

Once marriage had been achieved, campaigning organisations set out first to provide and then enforce teaching programmes which set out to acclimatise pre-pubescent school children to gay relationships. But this could only be done by the sexualisation of children who before adolescence would have hitherto been protected from this early exposure to sexualised relationships.

In the public sphere, any employee of the state who retained reservations about the ethical, religious or practical implications of same-sex marriage had difficulties in retaining or gaining employment.

None of these serious and far-reaching consequences were foreseen when equalities legislation was embarked on as a matter of civic generosity to same-sex couples.

The experience of abortion and same-sex marriage ought to have taught us a few lessons about the hidden and unforeseen effects of moving or removing the ethical boundaries in a culture formed on the long and steady insights provided by the Judaeo-Christian values that underlay our civilisation.

The Assisted Dying Bill, which is of course a euphemism itself, is predicated on progressives believing that there will be only one outcome from allowing suicide to be assisted - and that's a good one.

But there are two possibilities which are clearly foreseeable and which on their own ought to cause the most serious hesitations.

The first is in the patient/doctor relationship. Overnight doctors will be changed from people whose prime purpose is to heal, protect and help, to ambiguous figures who might either prolong life or take life. The fear and threat that this will inject into the doctor patient relationship will have the most profound consequences for medicine and for patients.

The second is that it will be impossible to avoid the growing sense of responsibility on elderly patients who have become ill, terminally or not, to relieve either their families or society of the economic cost and social burden they feel they must represent.

Already the pressure is growing in social commentary to hold the older generation accountable for and guilty of the abuse of resources the younger generation has less access to - housing and pensions in particular. Of course no mention of the horror of the shadow of nuclear war, the terror of rampant inflation and unemployment, or the recognition that each generation has its own advantages and disadvantages to face.

But if the attribution of guilt and privilege has already started, this is likely to have devastating consequences on the vulnerable elderly who would be accused of soaking up resources that should in justice be spent on the young. There could be a fairer solution to finite resources if only the elderly and infirm could be encouraged to do the decent thing and shuffle off the mortal coil.

Will the slippery slope into death become steeper? Would euthanasia and assisted suicide suffer the same slippage of regulation as the other contested ethical areas we looked at?

It has already started.

Already in some European states euthanasia has become legal and a recent research paper by Dr J Pereira documents the almost instant erosion of safeguards:

"The present paper provides evidence that these laws and safeguards are regularly ignored and transgressed in all the jurisdictions and that transgressions are not prosecuted. For example, about 900 people annually are administered lethal substances without having given explicit consent, and in one jurisdiction, almost 50% of cases of euthanasia are not reported. Increased tolerance of transgressions in societies with such laws represents a social "slippery slope," as do changes to the laws and criteria that followed legalization. Although the initial intent was to limit euthanasia and assisted suicide to a last-resort option for a very small number of terminally ill people, some jurisdictions now extend the practice to new-borns, children, and people with dementia. A terminal illness is no longer a prerequisite. In the Netherlands, euthanasia for anyone over the age of 70 who is "tired of living" is now being considered. Legalizing euthanasia and assisted suicide therefore places many people at risk, affects the values of society over time, and does not provide controls and safeguards."

In Holland as long as the patient is at least 16, no other person's consent except the patient's is mandatory (parents of 16- and 17-year-olds are involved in the discussion, but their permission is not required). Patients as young as 12 can seek euthanasia with parental consent. In about 10 cases since 2002, children aged 12 to 17 have received euthanasia; there is however no mechanism for refusing death to teenagers suffering depression and personality disorders.

One of the main ethical objections to legalising euthanasia is that the most coherent advocates of it are wealthy, well-resourced people who want to change the law to help people escape the worry of unnecessary suffering. But when they have succeeded, the people who will pay the price for this will be the vulnerable elderly, the frail and unwanted who all too easily will feel their lives are disposable; and at the other end, the wounded teenagers, overcome by existential angst and despair, who would survive if the state had not made access to death during a temporary period of depression so tragically accessible.

The Bible opens by posing a profound existential question to humanity. If you want to understand the dilemmas humanity faces, ask yourself the question of whether or not society can cope with the consequences of its choices? The account of the fruit of the tree which introduces us to the burden of recognising good and evil without the resources to be sure we can tell or handle the difference, should act as a challenging introduction to what the Bible calls 'the Fall.'

It should cause a hubristic society bent on thrusting back the ethical barriers that constrain it to pause before it unleashes unforeseen consequences. Even the Greeks, with a more primitive ethical narrative, warned each other about what lay hidden at the bottom of Pandora's box.

If our society changes the law in a way that undermines the sanctity of human life and legitimises utilitarian solutions which diminish the irreplaceable value of each human person, the consequences are likely to be the creation of a society that is more inhuman and more dehumanising. The Church should be at the forefront of a passionate opposition.

Dr Gavin Ashenden is a former chaplain to the Queen. He blogs at Ashenden.org