“Be on your guard against the yeast of the Pharisees and Sadducees.” Matthew 16.6
When Jesus warned his disciples to be on their guard against the yeast of the Pharisees, he was warning them to be careful of the negativity that could so easily spread through their whole lives. In particular, he may have been warning them against unbelief, which seems to be the context for his words.
The disciples were aware of the lack of food in their boat. Interestingly, in a short space of time they had witnessed two staggering miracles about the provision of food – the feeding of the 5000 and the feeding of the 4000. So why were they so worried about the 12 of them? Perhaps they simply did not make the connection and believe that Jesus would look after them. Good old-fashioned unbelief is a powerful force that can work through every area of our lives if we let it. Once it takes root, doubt often follows and pretty soon cynicism creeps in as well – does God really care and why would he be concerned about me?
Back to the disciples! The easiest and most obvious thing would have been for them to look at the person who was in the boat with them, rather than at the bread that wasn’t there! We need to learn a similar lesson and open our eyes to the presence of Jesus with us at all times, and begin to rely on him so that we do not let unbelief take a foothold in our lives.