Catholic bishops have said that free speech on issues such as abortion, assisted suicide and human trafficking must be at the centre of elections.

In a turn that would have taken the British utilitarian John Stuart Mill by surprise, the Bishops say that if Scotland is to be “a tolerant, open, diverse country then we must be free to discuss and debate ideas, even those which are deemed by some to be controversial”.

In a pre-election pastoral letter the bishops urge Catholics to play their part “in putting human life and the inviolable dignity of the human person at the centre of Scotland’s political discourse” and to warn politicians against imposing “unjust restrictions on free speech, free expression and freedom of thought, conscience and religion”.

In a 1,000-word letter distributed online and via 500 parishes, the bishops ask Catholic voters to give consideration to six key areas, when selecting a candidate. These include the beginning and end of life, poverty, family and work, free speech, Catholic schools and the environment. They say that “society relies on the building block of the family to exist and flourish” and that “government should respond to this reality with policies creating economic and fiscal advantages for families with children”.