"Until now, fraternity has meant holding back someone who wanted to commit suicide and accompanying them to the end.
Would it now mean watching the suicide or helping to commit it?" criticised the CEF Chairman and Archbishop of Reims, Eric de Moulins Beaufort, in the Sunday newspaper "Le Journal du Dimanche".
President Emmanuel Macron has described the law, which is intended to enable euthanasia and will be debated in parliament on 17 May, as a "law of fraternity".
Moulins Beaufort said he was expecting a tough battle.
The Archbishop expressed concern about manoeuvres by certain economic forces behind the legislative initiative and called the planned regulation a deception. "Quite directly, it will change our healthcare system."
Regarding the planned criteria for access to euthanasia, he said that these only showed some people the obstacles that had to be overcome in order to have a suicide carried out. The example of countries that have taken the step towards euthanasia or assisted suicide shows the inevitability of this change, said the Archbishop of Reims.
According to Macron, terminally ill adults in the final stages of their illness should in future be able to ask for help to die.
The patient would have to be fully capable of judgement, i.e. neither a minor nor mentally ill.
Active euthanasia should then be carried out using a lethal preparation that the person wishing to die ingests independently or with the help of another person.
Until now, the law in France has only allowed terminally ill patients to be permanently sedated at the end of their lives and to have their devices switched off.
Cases of seriously ill people who want to die or whose relatives want them to die repeatedly cause heated public debate.