The Church hierarchy said every citizen should be concerned about legislation on when terminations can be carried out and that this is a defining moment for the country.
A statement from the Irish Bishops' Conference said they wanted to challenge statements that the proposals are about saving lives.
"The right to life is the most fundamental of all rights; it is the foundation of all other rights. No individual has the right to destroy life and no state has the right to undermine the right to life," the bishops said.
"Yet the Irish Government is proposing abortion legislation that will fundamentally change the culture of medical practice in Ireland.
"For the first time legislation will be enacted permitting the deliberate and intentional killing of an unborn child. This represents a radical change. Every citizen, not just people of faith, should be deeply concerned."
The statement was issued as the bishops met for a second day at their June general meeting in Maynooth.
Last Saturday thousands of people demonstrated in Dublin to express support for the pro-life movement and their opposition to abortion.
The proposed legislation, which includes a provision for abortion to be carried out if a woman is suicidal, is expected to be passed into law by the summer.
The Irish Bishops Conference said Catholic teaching on medical intervention is clear.
"Where a seriously ill pregnant woman needs medical treatment which may put the life of her baby at risk, such treatments are ethically permissible provided every effort is made to save both the mother and her baby," the bishops said.
"This is different from abortion which is the direct and intentional taking of the innocent life of the unborn. No matter what legislation is passed in any country, abortion is, and always will be, gravely wrong."
The
bishops also claimed that the Government is under no obligation to
legislate for the 1992 Supreme Court X case where a 14-year-old sought
access to a termination after being raped.
"People are
being misled. We challenge repeated statements that this legislation is
about saving lives and involves no change to the law or practice on
abortion," the bishops said.
"Legalising the direct and
intentional destruction of the life of an unborn baby can never be
described as 'life-saving' or 'pro-life'."
The bishops claimed the legislation was "contrary to clear psychiatric evidence".
They said it is possible to envisage the deliberate destruction of a child right up to the moment of birth.
They claimed any loosening of a ban on abortion will open the door to ever wider availability.
The
bishops called for enhanced medical guidelines, which do not envisage
abortion, to provide clarity and a morally, legally and medically
acceptable way forward.
They also raised the issue of
freedom of conscience and the need for the State to respect the
principles of its citizens, including politicians, on the issue of
abortions.
They also warned that hospitals, doctors and
nurses with certain religious beliefs and ethos should not be forced to
ask for a patient to be treated in another institution or by other
medics.
"It is ethically unacceptable to expect doctors,
nurses and others who have conscientious objections to nominate others
to take their place. Neither should any institution with a pro-life
ethos be forced to provide abortion services," the bishops said.