Why do we need a sign for faith?

The demand for signs, as illustrated by the Jews in John 2:18, stems from human unbelief and spiritual blindness. Jesus' response highlights that all the signs required for faith are encapsulated in His resurrection—what Paul later refers to in 1 Corinthians 15 as the gospel. The resurrection itself is the sign. Believers are called to rest in the authority of God's Word rather than seeking additional validations. Therefore, faith does not hinge on experiences but rather solely on the truth of Christ and His accomplished work.