What does the Bible say about signs and faith?

In Matthew 12, Jesus rebukes the evil and adulterous generation that seeks a sign, emphasizing that true faith is grounded in the Word of God rather than in miraculous signs. He points to the sign of Jonah, indicating that His death and resurrection will be the ultimate sign of His authority. This is further echoed in 1 Corinthians 1, where it is stated that 'it pleased God by the foolishness of preaching to save them that believe.' Thus, faith is nourished and sustained through the preaching of the gospel, and not by seeking after signs.