There was a story a few days ago on Digg (it's still there) that I Dugg. It was about the director of the Titanic movie being involved with the documentary of an archaeological find that's being publicized as Jesus's coffin. The story I Dugg still only has single-digit Diggs, whereas another story about the exact same subject is on the Most Popular Last 24 Hours list with thousands of Diggs. The message is the same in each, but it doesn't matter for one of them because the headline and summary were not written in an interesting enough way to get people to click through to the story.
Same thing happened in church today. Last week, at one of the 2 churches I split my time between, I could have told you every single detail about that day's message - and I did, to lots of friends and family. Today, however, at the other church, try as I might, I couldn't make my mind stop wandering to other thoughts, chores, the rest of the afternoon, last week's posts, etc. After he was done speaking, I asked my wife what he was just talking about, and she told me about the Bible verse he started with (which I DID remember), but couldn't tell me what exactly he was talking about in relation to that verse.
Be interesting, say interesting things, write interesting words, and people will remember what you attempted to communicate. Otherwise, your message will be forgotten, or never even seen or heard in the first place.