Through their devoted study of the scriptures, the Pharisees had a pretty good idea how to recognize the Messiah, but for some strange reason, they did not recognize Jesus as Messiah. Ironically, the scriptures they studied even told them they wouldn’t:
Be ever hearing, but never understanding; be ever seeing, but never perceiving (Isaiah 6:9
English: World English Bible - WEB 
9 He said, “Go, and tell this people, ‘You hear indeed, But don’t understand; And you see indeed, But don’t perceive.’
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So eyes spiritually shut tight, ears spiritually closed to the signs, they continued in their intellectually lazy tests, this time asking for a sign from heaven. Mark, who wrote this Gospel, has recounted several signs to this point: healing the sick, feeding thousands, and teaching with authority unlike any they’d known in over 400 years (since the age of the prophets).
As we examine the way in which these devoted men conducted themselves, it’s a sign in itself that they didn’t recognize the Messiah. And it’s also cause for self-examination:
- What is God doing right before my very eyes that my pride has made me blind from seeing?
- What great wisdom am I denied because I chose the wisdom of the world instead?
When you pray, don’t ask for signs from heaven. Open your eyes to the obvious proofs of God’s existence; open your ears to His Word, the Bible. Study prayerfully and tirelessly so that you won’t become blinded by pride of life and deafened by the wisdom of this world.