The Oxford way of teaching, with its deconstructing, analytical approach, proved fatal, he says, to his assumption as "a naively dogmatic young atheist ... that atheism is exactly the same as 'common sense' or objectivity. I'm not saying that in psychological terms we can't be objective.
The Oxford method of teaching, which emphasizes analysis and deconstruction, led the speaker to realize his naive assumption that atheism is equivalent to "common sense" or objectivity. He acknowledges that we may not always be able to achieve psychological objectivity but believes it's possible to be objective in other ways.