It is not difficult to summarize the parts that people object to. The thing most object to is the assertion of common descent, followed by Darwin's mechanism, natural selection.
Well, true. But the assertion of common descent may be considered the observed "fact" of evolution, and natural selection is really only one piece of the theoretical puzzle underlying this factual observation. Perhaps they are relatively easy to summarize because they are relatively easy initial concepts to comprehend. Once you step past this threshold -- well, for me it can get kinda' hard.
But then, I'm not the best person against whom to gauge ease of scientific comprehension, suffering as I do from what my wife calls "acute hebetude".