A Free Church of Scotland minister has denounced the SNP as “Satanic” and urged his congregation to “think long and hard” if they are considering backing the Nationalists in next week’s Holyrood election.

Rev Paul Gibson, of Knox Church in Perth, said the Scottish Government’s plans to allow adults or children to legally change their gender so they are neither men nor women was one of the worst “attacks on Christianity” the country has ever seen.

In an outspoken letter to his congregation, he also said the SNP’s plan to assign every child a state guardian usurped the God-given role of parents. He added: ““Can a government really be this foolish and that Satanic?! The answer, tragically, is yes.”

Although he admitted there was a “good deal of truth” to the saying that all political parties are as bad as each other, Rev Gibson questioned whether “true believers” could vote for the SNP “in good conscience before our creator.”

He also warned that the church must brace itself for “the most extreme attack against God’s good order” in living memory, given that the Nationalists appear certain to win another term in office next week.

His incendiary intervention came after Nicola Sturgeon disclosed last month that one of her top priorities after she wins next week will be to review Scotland’s gender recognition laws to ensure they are in line with “international best practice”.