The sermon explores the growing opposition to Jesus from the Pharisees and Sadducees. These two religious groups, usually at odds with each other, unite in their rejection of Jesus because he threatens their power. Despite witnessing his miracles, they demand a special "sign from heaven" to believe in his divine authority, but their request is disingenuous. Jesus rebukes their stubborn unbelief, comparing their blindness to interpreting weather signs while missing the clear signs of God’s work in his ministry. He warns the disciples to be wary of the “leaven” or false teachings of these leaders, which stem from self-righteousness and self-indulgence. Ultimately, Jesus points to his resurrection as the ultimate sign—the "sign of Jonah"—proving his identity as the Messiah.