Bishop John Keenan, President of the Bishops’ Conference of Scotland, is urging members of the Scottish Parliament to think of the vulnerable and vote against assisted suicide.
He said that MSPs face the "binary choice" of permitting a "new autonomy for some" or protecting thousands of "fearful" Scots.
On Tuesday, MSPs will be voting for the final time on Liam McArthur's Assisted Dying for Terminally Ill Adults (Scotland) Bill, which would make it legal for terminally ill adults in Scotland to seek an assisted suicide.
Bishop Keenan said that voting in favour of McArthur's bill would "change healthcare forever" in Scotland.
"The Scottish Parliament stands at a moment of profound moral consequence," he said.
"This Bill is a serious threat to vulnerable Scots, including the elderly, disabled, those who suffer from poor mental health, and victims of domestic abuse. In a world that often prizes independence, those who are vulnerable can easily feel like a burden."
He expressed disappointment that MSPs have failed to back a number of safeguards, including one that would have prevented doctors from being able to raise assisted suicide unprompted with patients, a decision he said "dismantles thousands of years of Hippocratic tradition of ‘first do no harm’".
"This decision only adds to already significant concerns expressed by MSPs about the risk of coercion, demonstrating a keen awareness of their responsibility to protect vulnerable people from this threat," he said.
"The crucial conscientious objection clauses that offered protection to doctors have been stripped out of the Bill which means MSPs will be asked to vote on an incomplete Bill devoid of a key protection for healthcare workers."
He noted that the failure to include this safeguard has prompted both the Royal College of Psychiatrists in Scotland and the Royal Pharmaceutical Society of Scotland to move from a position of neutrality to formal opposition to the Bill.
Another measure that MSPs failed to back and which is of great consequence to the Catholic Church would have allowed institutions to opt out. Without this measure, Catholic hospices and care homes face having to be involved in assisted suicides against their will, or else close down.
The unnecessary closure of Catholic hospices and care homes would be "a hammer blow to an already creaking palliative care system", he said.
"True compassion is not found in killing but in walking with those who suffer, ensuring they receive the medical, emotional, and spiritual care that affirms their inherent worth," he said.
"Every person - regardless of age, illness, disability, or circumstance - is a gift from God," he said.
"There is no such thing as a life without value. Our task as a society is not to eliminate suffering by eliminating the sufferer, but to surround every individual with love, support, and dignity until their natural end.
"I understand how the choice before our MSPs is unenviable, because it is now a binary one; either they vote to allow some citizens a new autonomy, or they vote to protect thousands of vulnerable and fearful Scots who do not want this legislation and who will suffer most if this Bill passes.
"They cannot do both at the same time, and I would urge them, in the last analysis, to think of those who, in the months and years ahead, will find themselves defenceless and who, at this moment, are depending on them most.
Christian charity, CARE for Scotland, echoed these concerns, calling the Bill "dangerous, divisive and damaging". It is also appealing to MSPs to vote the legislation down and instead focus efforts to improve access to palliative care.
CARE for Scotland Policy Officer, Michael Veitch, said: “There is no doubt that assisted suicide will harm the most vulnerable across Scotland.
“Our history as a nation cries out against this approach. We have a legacy of being caring and compassionate, but assisted suicide is the very opposite.
“We urge MSPs to consider the stakes that are involved."
He continued, “MSPs should listen to the opinions of those who would be most impacted by assisted suicide, including those living with a disability.
“Their view is clear: this is a dangerous Bill that will make them feel a burden.
“I urge MSPs to shut the door on assisted suicide and focus efforts and energy on improving access to palliative care across Scotland.”
