Theists constantly make the point that secularism implies purposelessness, but modern culture seems to sweep this away with the reply that individuals make their own meanings for living. I think this backfires on secularism.
Think about it. If men make their own reasons for living, what a sorry choice secularists have made. If Rand's worldview was correct, she has nothing to show for defending it. Most importantly, if secularism were true, truth itself would be overrated; I would have no non-arbitrary reason for accepting truth. Or, at least, I could have my own reasons, purposes, or created meanings for the selective acceptance of truth. I would only accept what I would want to be true - in other words, not secularism.
Maybe this selectivity would be self-defeating, but if secularism is true, so what? Does secularism imply some sort of obligation to defending truth? No.
So when you mention this to a secularist and the reply is condescension, just point out that his condescension follows from his and only his reason[s] for living. Since that secularist would agree - at least, he would if he were as "logical" as his condescension would imply - with the more fundamental principle that his reason for living is no less subjective than mine, he has no basis for refusing me my reasons for rejecting certain truths.