"A wicked and adulterous generation looks for a sign, but none will be given it except the sign of Jonah."- Matthew 16:4
Jesus replied with this to the Pharisees and Sadducees when they asked Him to give them a sign from heaven. I ask God for signs many times for guidance or direction in a situation. Jesus gave many signs throughout His ministry on Earth, so I believe we can certainly expect more through the Holy Spirit. But the Pharisees and Sadducees were testing Jesus, and pushed Him to try and prove Himself. They were blind to all the signs and teachings that had already happened. Jesus said they will be given the signs of Jonah.
"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 and three nights in the heart of the earth. The men of Nineveh will stand up at the judgment with this generation and condemn it; for they repented at the preaching of Jonah, and now something greater than Jonah is here. " -Matthew 12:40-41
It seems Jesus was saying that the only chance of them seeing a sign was for them to witness His death and resurrection. Only then would their hearts soften to repent and believe in who He is.
Jesus died, rose from the dead, and gave us an advocate to be with us and help us share the love of Christ. That advocate is the Holy Spirit. We are given gifts through the Spirit to enable us to show signs of great love to our neighbors and enemies, that we could not show on our own.
So what does this all mean now? Well, to me it means that we should be the sign for our generation. People should be able to see the finished work of Jesus Christ through us in how we react to others, and through our lifestyles. So I encourage you to submit to the Holy Spirit to be a sign to this generation, and make people wonder how you can love others so radically!