Q: Can a atheistic materialist have sacred things?
A: Yes, and that's not even hard question. That doesn't even require holding two mutually contradictory beliefs in your head at the same time. (Am I a atheistic materialist? Most of the time. Does it matter? I don't think so).
So, let's say you are an atheist, maybe even an apneumatist. (Or is it apneumist? Or aphasmist? Which is to say you don't believe in the survival of personality beyond death). The two issues are independent of each, in fact orthogonal.
So, you don't believe in God. Period. You are in the No God column, and may or not be in the No Soul row. So, the universe is miraculously created out of nothing, as far as the evidence suggests. And you, dear reader, miraculously appeared out of the something which was formerly nothing. And in the vast amount of time the universe is here, which is considerable, you appear with relatively less duration than the most ephemeral of virtual particles.
Which should suggest, at least it does to me, that every single teeny tiniest piece of time -
the Planck time - that you exist, is precious, because the immense yawning voids of your non-existence stretch before and after you. Because that.
Did I say precious? How about sacred?
And what do you do? You waste time. You watch TV. You do all sorts of meaningless things that add no meaning to an existence that may or not be crying out for meaning. (I'm assuming a certain existentialism calls for trying to provide meaning to life. Or you could be a nihilist. In which case, wow, do whatever you want, I guess).
So, you are a lazy atheist. By your own logic, you are committing a sacrilege by wasting time, So, know sin. It that bad? Hey, it's your precious time to waste, your sacred existence to let slip through your fingers. Why should you care? Should you care?