Yes. In Mere Christianity he calls it the most intellectually bankrupt of all “religious” beliefs.
You might remember his observation that there are necessarily three logical possibilities: Jesus Christ was either a liar, a madman or simply a person telling the truth.
The problem faced by the atheist is that he must deny—to himself—that he lacks confidence in his own ideology, meanwhile it’s this very lack of confidence which limits his access to the intellectual realm of the debate.