Cardinal Keith O'Brien was one of the 30 leading religious figures along with former Archbishop of Canterbury George Carey to draw up the Westminster 2010 Declaration which sought to turn the Christian vote into a more unified political force.
His anger over the interference of party leaders on matters of conscience comes as he today unveils a questionnaire for candidates in Scotland asking them to indicate where they stand on issues of faith.
The Westminster 2010 document was based on an American initiative last year called the Manhattan Declaration and asked candidates to support family values, oppose abortion, assisted suicide and euthanasia.
The Scotsman learnt of the edict by party leaders from one of the organisers of the declaration, who described it as "shocking interference on matters of individual conscience".
Candidates have contacted the Westminster 2010 organisers to apologise for not signing and there are allegations that some were leaned on not to put their names to the document.
Today the Catholic Church in Scotland has issued a similar document asking candidates to tick a preference box on five key issues of the rights of the unborn child, social justice, religious freedom, the family and end of life issues. Last night a spokesman for the Church said: "It is a matter of some concern and disappointment the national leaders of the Labour, Conservative and Liberal Democrat parties have barred their candidates from signing this declaration.
"It is interesting to note that the SNP has quite rightly described it as a matter of conscience."
A spokeswoman for the Conservative Party confirmed that candidates had been advised not to sign Westminster 2010.
A Labour Party spokesman claimed that the ban was part of a wider policy for candidates.
The Liberal Democrats denied there was a ban on candidates signing it.
THE Catholic Parliamentary Office has circulated a questionnaire to all Scottish candidates, asking them their views on five issues:
Rights of the unborn
&149 Assisted suicide and euthanasia
Candidates are asked to choose one of the following answers to each question: agree strongly; agree slightly; neither agree nor disagree; disagree slightly or disagree strongly.