In previous verses, the author of Hebrews describes the priest-like nature of Jesus. In fact he identifies Jesus as the "ultimate" high priest, who acts as a flawless go-between for us and God. The author also says that Jesus is a priest "in the order of Melchizedek", which he will expand on in chapter 7. Until then, he takes a detour.
The word "this" in verse 11, the subject of which the author says he has "much to say", is not perfectly clear. It may be specifically referring to the comparison between Jesus and Melchizedek. But it may also be referring to Jesus in general, and how he lived his life as a model for us, living life more effectively than any person before him(the general context of Hebrews up to this point).
In either case, the author first tells his readers the explanation of these things is difficult. Why? Because his readers "have become dull of hearing". The Greek word for "dull" here means "slow" or "sluggish". The original readers of Hebrews became slow to truly listen and respond to truth.
It seems this letter was written to those who have been believers for a significant amount of time. Long enough that they ought to be teaching others. Instead, their lack of true interest and commitment to truth left them needing to be taught, again, the most basic truths that have been revealed regarding Jesus and what it means to follow him.
"Oracles" were generally brief, divine utterances. So the first readers of Hebrews were not only behind in understanding the basics of the faith. They were behind in understanding them on their most basic level!
The author uses the metaphor of milk and solid food, implying that the readers are still requiring the spiritual food of spiritual infants when they should be taking in the spiritual food of spiritually mature adults.
The author explains his metaphor more clearly, stating that a defining characteristic of a spiritual infant is a lack of skill (more directly translated "experience") in "the word of righteousness". It's not crystal clear what "word of righteousness" refers to here. But given the context, it seems likely that it is describing the teachings from scripture that inform us how to live in alignment with God's will and plan.
Whether we are gifted with an ability to teach or not, we should each develop enough experience with scripture that we are able to help others become more acquainted with God's intention for our lives. To the degree we are unable to do this we should expect to be classified as spiritual babies. (Ouch! That stings me a bit. But I expect that was part of the author's intention.)
By contrast, one mark of the spiritually mature is the growing ability to constantly and accurately distinguish good from evil. As geeks who hope to gain more spiritual maturity, we should aim to be constantly discerning our way through the entertainment content we take in, evaluating the positive or negative effects it may be having on us. We should also be continually discerning the ideas and teaching we take in, whether from entertainment, a scholarly book, seminary professor, Sunday morning preacher, or some guy on the Internet. ;-)
Likewise, since many of us geeks love to talk and share opinions, we should carefully evaluate the ideas or opinions we express(preferably before we express them).
It might seem strange or silly, but sometimes we can be so fascinated or moved by an entertainment experience we've had that the ideas taught or affirmed in that experience are absorbed and adopted without us realizing it. Even though I think of myself as someone who is in the habit of evaluating the ideas presented to me, I'm far from immune to this.
I remember early on when I was evaluating various views of free will and predestination I was influenced by The Matrix: Reloaded. In one scene, Neo, Trinity and Morpheus sit down with the Merovingian, who launches into a speech about cause and effect, presenting choice as an illusion. At the time, the arguments for Calvanism were beginning to persuade me and I suspect my love for the Matrix Trilogy won me over to that view for a time. (If you're curious, I currently subscribe to a both/and view of free will and predestination, since I believe scripture teaches both and our growing understanding of higher dimensional physics allows for both to logically cooperate. For more, read "Beyond The Cosmos" by Dr. Hugh Ross)
I've likewise heard other professing Christians talk about their views of spiritual matters, citing fictional supernatural stories(Buffy, Supernatural, etc.) as illustrations. While fiction CAN be useful as illustration, it's important that we use reasoning and fact-finding independent of entertainment sources to come to conclusions about what we believe or allow room for in the realm of possibility.
To many people, hardcore geeks give the impression that their lives are shaped by the entertainment they enjoy in seclusion or only with other geeks like them. They seem content to remain in the worlds they create for themselves, with little time or interest in engaging with others. I know this doesn't describe all hardcore Christian geeks. Maybe not even a majority. But it's a pattern that should give us reason to evaluate ourselves. I've met a number of geeks who seem to be "stuck" in one place spiritually, devoting time and energy to their geek hobbies but not practically and purposefully pursuing maturity in their faith.
Wouldn't it be awesome if the Christian Hardcore Geek was known for a friendly and infectious (rather than secluded) love of geekery? What if Christian Geeks were known most for their insight to scripture and for shaping their lives after it? What if Christian Geeks were known as the go-to believers when someone needs to find answers in scripture about the big, small and intense questions in life?
That's the vision that God has for you and me. May he give us undeserved favor as we step out of our comfort zones to pursue the solid food of spiritual maturity.