Sermons are not necessarily difficult to write, there is a LOT of materials in commentaries and other reference books. My process is three-fold. In the first two steps, I either read far and wide from those more knowledgeable than I. In this stage, I may also listen to the teachings of other pastors on the topic/text at hand. The second step is to put down what I think of the text, in a sense draft my own commentary of the topic or text. The third step is compiling all the gathered wisdom, putting it in order and arranging it in a sensible manner so that it is useful to the hearer. Often I harvest an idea of the application, or purpose of the message in the first two steps. Other times I do not, or I go the wrong way, or I think I have it but I do not. Those instances make for a difficult sermon-writing. Mk 7:23-37 is such a sermon. The text is not complex – Jesus heals a girl at the faithful request of her mother (lesson: prayer, how to treat Gentiles) and then Jesus heals a Gentile man (lesson how to treat Gentiles…I think). But it will not come together, but the Lord is faithful. Sunday is still some days away.
Continue to pray.