“A wicked and adulterous generation seeks after a sign, and no sign shall be given to it except the sign of the prophet Jonah.” And He left them and departed. Matthew 16:4
This vignette between Jesus and the religious leaders of the day clearly distinguishes between living by faith or accepting Christ by a sign.

By asking for a sign the religious leaders were demanding proof of the divinity of Jesus. They would not accept Jesus by faith.
Jesus used the analogy of the weather condition to explain their actions of unbelief. He said you can look with your eyes to discern if the weather today is going to be sunny or stormy.
Jesus calls them hypocrites because they will only believe what they can see. In other words, they can see the condition of the sky but are blinded to the spiritual signs of the times.
Then Jesus calls them a wicked and adulterous generation because they insist on a sign to believe in Him. Jesus refutes their unbelief and says no sign will be given except the sign of Jonah who laid inside a whale for three days before he was set free.
Jesus uses the term “wicked and adulterous” because the religious leaders insisted on worshipping the outcome of the blessings of God but were not willing to live by faith in Jesus who is the author of the blessings. Their hidden interest was in worldly things like power, prestige, and prosperity.
This is a perfect example of how twisted motives have crept into religion. As a believer you choose to worship Jesus for who He is and not what you can get out of Him.
You will find the signs of the times by walking with Jesus and yielding to the Holy Spirit!
The spiritual man judges all things but is judged by no one!