Mr Robertson made his plea following the move to devolve abortion law from Westminster to Holyrood.
The Free Church of Scotland, which attracts around 13,000 worshippers on a Sunday, has a pro-life stance, opposing abortion on moral grounds.
Mr Robertson urged the discussion to encompass the rights of fathers and most importantly the child in the womb as well as women’s rights. “Given that babies can survive at 24 weeks outside the womb, is there any scientific or logical reason not to reduce the age limit? Are France, Germany and Italy with their 12-week limits any less “progressive” than Scotland?” Mr Robertson asked.
In the UK abortion is legal until 24 weeks under the 1967 Abortion Act.
Mr Robertson added: “Today we look with horror at how “civilised” society could acquiesce in and support the evil of slavery.
“In the future I believe we will look back with horror at the way that society, despite our increased scientific knowledge about the status of the child in the womb, has acquiesced in the evil of abortion. “If we want a more enlightened approach then perhaps we need to begin a more enlightened conversation, with people on all sides trying to think about the welfare of all people, and not just the fundamentalist views of their particular political or religious tribe. Or is that a conversation too far for our tolerant liberals and ‘compassionate’ conservatives?”