I think we are often amazed when people do not believe in the Lord Jesus Christ. We forget that our eyes have been opened by the Holy Spirit to see the Lord and His truth. We forget just how spiritually blind those in the world are without the Holy Spirit illuminating their eyes.
We see it here. The Jews are witnesses to Lazarus’ resurrection from the dead, but they are not changed at all. In fact they actually become harder in their views to Jesus. Not only were they going to kill Jesus, they now wanted to kill Lazarus because he was a living example of the power of Jesus and now many were believing in Jesus because of him.
They should have believed, but they were blind. We must make sure we believe and seek the help of the Holy Spirit to see and understand the truths of God as they have been revealed in the Bible.
Consider: Mark 8:14-21, Luke 16:31