Throughout the Gospels, people kept nipping at the heels of Jesus, demanding a sign. Even after healings and feedings and all sorts of miracles, they kept coming back asking for a sign.
For example, MT 12:38+
"38 Then some of the Pharisees and teachers of the law said to him, “Teacher, we want to see a sign from you.”
39 He answered, “A wicked and adulterous generation asks for a sign! But none will be given it except the sign of the prophet Jonah. 40 For as Jonah was three days and three nights in the belly of a huge fish, so the Son of Man will be three days in the heart of the earth. …"
And even today, people overlook God’s miracles all around them, but instead keep asking for signs. In the Gospel of Luke, at the conclusion of the parable of Lazarus and the rich man, Jesus points this out:
"27 “He answered, ‘Then I beg you, father, send Lazarus to my family, 28 for I have five brothers. Let him warn them, so that they will not also come to this place of torment.’
29 “Abraham replied, ‘They have Moses and the Prophets; let them listen to them.’
30 “‘No, father Abraham,’ he said, ‘but if someone from the dead goes to them, they will repent.’
31 “He said to him, ‘If they do not listen to Moses and the Prophets, they will not be convinced even if someone rises from the dead.’” " (LK 16:27+)
Is there any doubt what Jesus was referring to in those last 7 words?
Yes, God hitting me in the head with a brick would make it easy to believe. (At least that’s what I hope for! In fact, my wife is going to put a brick in my coffin because I’ve said this so much!) But Jesus tells us we don’t need that, in the gospel story of Doubting Thomas:
Then Jesus told him, “Because you have seen me, you have believed; blessed are those who have not seen and yet have believed.” (JN 20:29)
We have been given what we need to choose faith (or reject it.) It’s up to us whether we want to be the Pharisee/Scribe, or the the man hoping that his son could be cured:
Immediately the boy’s father exclaimed, “I do believe; help me overcome my unbelief!” (MK 9:24)