Relevance?

I went for a walk today and I walked into a local Christian book store looking for a biography on David Livingstone which they did not have. What did catch my eye though was their most prominent bookshelf with the heading "Relevant". And I smiled. And I thought: 'hmmm should I assume than that the rest of the books in this store are therefore irrelevant or somehow less relevant?'

What does that mean?

For me the real amusement, and maybe this is letting my own theological colours out, was that I'd have probably marked said section "Irrelevant"...!