Simplistic Secularism

I'm reading a collection of articles from the Irish Times gathered in a collection called Christianity. Some of the articles seem quite interesting, but they largely involve looking 'from without' upon Christianity as a religious phenomenon, rather than engaging in theology 'from within'. One article really struck me though - it's by David Kelso, a Scottish secular humanist. He's clearly a very intelligent and cultured man, and writes in a compelling style. When he gets onto the topic of religion however, he abandons all nuance and subtlety and adopts a simplistic and (apparently) uninformed approach:

'Humanism is in many ways a natural alternative for those disillusioned with Catholicism. Revelation is replaced by reason; absolute authority by pluralism and tolerance; superstitious tradition by progressive scepticism; and divine grace by human rights'.

Both humanism and Catholicism are caricatured here - I know many intolerant atheists, and many Catholics who are passionate about human rights.

Why is it that intelligent humanists lose their critical faculties and produce crude and clumsy arguments when it comes to religion?