He gained public attention following his critique of The God Delusion by Richard Dawkins[9] and has since become a commentator on religious, social, and political affairs in Scotland, with an annual readership of over one million.

[11] Robertson had originally planned a career in politics, intending to stand for the Social Democratic Party (SDP) in his home seat of Ross, Cromarty and Skye in the 1983 general election.

However, a failed bid to become Senior President of Edinburgh University Students Association precipitated a change in direction, and in August 1986 he became the youngest minister in the Free Church of Scotland (aged 24), while his contemporary Charles Kennedy went on to win the same seat he had hoped to contest, becoming the youngest Member of Parliament (aged 23) in the process.

[14] Robertson co-founded Solas (Centre for Public Christianity) in June 2010 with the former SNP leader, Gordon Wilson, who was a member of St Peter's Free Church in his final years.

[24] Robertson has a blog, The Wee Flea, the name of which alludes both to Richard Dawkins' description of Robertson, John Lennox, and Alister McGrath as "fleas living off a dog's back", and to the Scottish colloquialism "Wee Frees" - referring to the Free Church of Scotland.

[27] In 2014, 2015, and 2016,[28] Robertson was voted one of the 100 most influential Christians in the UK by online voters on "Archbishop Cranmer's Top 100 List".