You say this is a problem for materialism and I assume you include naturalism as well.
The problem I see is that your comment boils down to an argument from incredulity. It is not an abductive argument because you are appealing to the supernatural. Something that has no evidence in its favour (making it the least likely answer) but is also an unfalsifiable proposition. Magic / miracles can account for anything.
More importantly it merely pushes the question back one step. If complexity requires design, then why does not this intelligent author require a creator? By positing without justification that this creator (that usually aligns with one's ancient holy texts) doesn't require creation, or is eternal, then your argument runs foul of Occam's Razor by introducing an unnecessary extra assumption.
Nature itself only need be eternal, and we know at least that nature exists.