Jesus “sighed from the depth of his spirit.” I think we all know how Jesus felt. The Pharisees were pestering him for a sign. Of course, Jesus had, at least twice, fed crowds with a few loaves of bread and a couple fish. He healed the sick, the blind, and the deaf by the thousands. Still, the Pharisees were demanding a sign.
Jesus could have just given in. This must be at least partially where that sigh came from. Jesus knew that he could have said, “What do you want? Just name it.” He could change the color of the sky, turn mud into a person, summon 12 legions of angels, or whatever. He could literally have done anything. He could have just started taking requests and fulfilling them as they were spoken. The Pharisees want to test Jesus here; they want to try him out like we might try out a new gadget on Christmas day.
This demand for a sign shows a basic misunderstanding about faith. Faith is a gift from God. Faith is not something we do; faith is something God does to us. The Pharisees, like most people today, thought that their faith was the result of weighing both sides, thinking about it, and coming to a judgment. They are asking for a sign because they want more evidence before making their decision. But what evidence would have been sufficient? Anything can be thrown into question. Maybe it is just an illusion. Perhaps Jesus was a space alien with advanced technology. Maybe it was all just a dream. Maybe you are dreaming now and you will wake up in a minute and realize that this is all imaginary.
There is no argument, there is no evidence, that could convince us perfectly. Our brains are not perfect. If faith came from within us, it would have no surer footing than any other thought we have. Faith, however, comes from outside, from God. If we lack faith, we should not demand signs from God, we should not invent elaborate schemes to prove or disprove him. We ought to pray. If we ask God for faith, he can give it to us; he can give us a faith that does not rely on our weak intellect, that is not subject to the whims of our limited mind.