The Lib Dem manifesto states that they plan to: "Decriminalise abortion across the UK while retaining the existing 24-week limit and legislate for access to abortion facilities within Northern Ireland."
The Labour party says: "We will uphold women's reproductive rights and decriminalise abortions" and "Women in Northern Ireland should have access to abortions in Northern Ireland."
Vicars, members of General Synod, youth workers and academics from the Church of England signed a letter expressing their concerns at this.
383 people signed in time for publication on Thursday, with around 40 more offering their support afterwards.
The letter states: "These changes would amount to a declaration that a foetus was no longer a human being, worthy of the same protections against deliberate harm and termination of life."
The Anglican members call on the Church of England bishops to speak out against the policies, in the light of their own official teaching that says, "the foetus is a human life, with the potential to develop relationships, think, pray, choose and love."
Some bishops have already expressed their concerns with the policy proposal, such as Rt Rev Philip North, the Bishop of Burnley and Rt Rev Tony Robinson, Bishop of Wakefield.
The law states that abortion is legal up to 24 weeks, providing it is signed off by two doctors who think the woman's physical or mental health would be put at risk if the pregnancy continued.
After 24 weeks, abortions are only allowed if there is a fatal foetal abnormality, if the mother's life is in danger or if there is a danger of serious physical or mental injury.
Signatories include Prudence Dailey, a lay member of the General Synod; a retired midwife and Anglican worshipper Anne Evans; Jenny Rees, Associate Minister for Women at All Saints Church Crowborough and Rev Carol Smart from the Isle of Wight.
It also include Dr Lee Gattis, Director of Church Society; the retired Bishop of Burnley Rt Rev John Goddard; Dr Adrian Hilton, editor of the Archbishop Cramner blog and Rev Peter Ould.
The full letter reads:
"Sir, The Labour Party and the Liberal Democrats have, in their manifestos, proposed the decriminalisation of abortion. This would remove all sanctions in criminal law for those who perform abortions outside the limits set by the Abortion Act 1967.
"These changes would amount to a declaration that a foetus was no longer a human being, worthy of the same protections against deliberate harm and termination of life. In light of the Church of England's own teaching that "the foetus is a human life with the potential to develop relationships, think, pray, choose and love" and that the church "would like to see a drastic reduction in the number of abortions carried out and stricter interpretation of abortion law", we write, as members of the Church of England, lay and ordained, female and male, to express our sincere concerns about these proposals, and to call on the bishops of the church to do all they can to speak out against them."
You can red the full list of signatories on the Archbishop Cramner blog here.
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