Why the Pharisees were blind spiritually: Isa 6:9-10: Isaiah’s prophetic warnings were not heeded, and the people had already been warned, but they ignored the revealed word of God yet again, so God’s will would no longer be received. And he said, Go, and tell this people, Hear ye indeed, but understand not; And see ye indeed, but perceive not.
To avoid the trap of the Pharisees, we've got to guard the interconnection between our thoughts and our attitudes. - David Jeremiah
Blindness
Mark 2:1-12: They would not receive Jesus as God in the flesh, who was reaching people with the good news, Jesus, the savior of their sins.
Spiritual blindness comes when you try to discern this world's events without the word of God as your filter. Pastor Spada 1 Cor 2:14