Your assertion is partially correct. God is not seen but this woman's Christian faith is not based strictly on God whom cannot be seen. It is based on the legal-historical method of verification - same type of evidence used in courtrooms where the evidence and witness testimony is evaluated in order to determine the truth. Her Christian faith rises or falls on the proof/veracity of Jesus' resurrection as testified to by eye-witnesses whose testimonies are recorded in the Bible. Since the resurrection was a one-time event, the scientific method which requires repeatable, observable phenomena is not applicable.