The supreme court upheld the ban on assisted suicide (doctors helping patients to end their lives) on 25 June in response to three cases of appeal.

The cases by Paul Lamb, a quadriplegic requiring 24-hour care, Jane Nicklinson, widow of the right-to-die campaigner Tony Nicklinson, and a claimant known as 'Martin', petitioned for medical assistance to die.

The Care Not Killing alliance welcomed the ruling because they believe in providing the best possible care to people who are dying - killing the pain not the patient. The coalition is now urging people to act against a new bill in the House of Lords.

Parliament are now examining the predicament of those who are severely ill and wish to die but cannot do so without medical assistance.

Lord Falconer has announced a private members' assisted suicide bill which will be debated in the House of Lords on 18 July. If passed, the bill will grant assisted suicide for mentally competent adults who have six months, or less, to live.

Falconer, backed by Dignity in Dying, argues that his proposals are modest in comparison with Lamb's case as he is only asking for permission on behalf of the terminally ill. He claims that the changes will make it safer for vulnerable people and have "upfront safeguards" to prevent abuse.

Care Not Killing, of which the Evangelical Alliance is a part, strongly opposes this bill, warning others not to be fooled by the "modest" assisted suicide proposals.

There is a fear that if legalised in the UK, like what has happened in countries such as the Netherlands, Switzerland and Belgium, incremental extension can occur and it could lead to normalisation.

Dave Landrum, director of advocacy at the Alliance, said: "We must be on our guard against bill's like this which could too easily convince people that a small change in the law would be harmless. This is a classic slippery slope situation, and we must remain vigilant to value and protect life. I would really encourage people to contact their MP and a member of the House of Lords to show them why you care passionately about this issue.

"A change in UK law to allow assisted suicide would undoubtedly place pressure on vulnerable people to end their lives so as not to be a burden on others. Indeed, such pressures would be acutely felt by families who are struggling to make financial ends meet."

Dr Andrew Fergusson, spokesman for Care Not Killing, said: "As Paralympian Baroness Tanni Grey-Thompson and other disability rights campaigners have said, changing the law would be dangerous and discriminatory. It would send out a very clear message to those who are disabled, terminally ill, or just old, that their lives are less worth living and protecting than the lives of the young and healthy.

"The current law exists to protect the vulnerable and those without a voice: disabled, terminally ill and elderly people, who might otherwise feel pressured into ending their lives. It does not need changing."

Care not Killing are urging supporters to make their voices heard in opposition to the bill by writing to peers in the House of Lords through their website.

They are also urging people to sign the Not Dead Yet petition which challenges prime minister David Cameron to back up his declared opposition to assisted suicide. Some disabled people will gather outside parliament to lobby peers on 18 July.