This afternoon I had the great pleasure of hearing the physicist Jim al-Khalili speak to a packed house at the Cheltenham Festival of Science. He didn't cover anything particularly new, but he did recap ideas such as why we know the universe is expanding, why we know it has only existed for approximately 13.7 billion years, why it probably does not have borders and why the vacuum is not empty (in other words, that energy and matter are constantly springing into existence and vanishing back out again).
Naturally (unlike a preacher delivering a sermon) he took questions afterwards. Good ones were asked, and straightforward answers given.
The advantage of listening to a good communicator is that he can make somewhat difficult concepts understandable, and encourage anyone with any curiosity about the subject to go on from there to learn more on their own. What is more of a challenge is encouraging anyone with a fixed, simplistic worldview based on authoritarian ignorance to open their eyes even just a fraction.