Hook: Which part of human nature disappoints you the most?

Book: Evidently, some of the people who witnessed the dramatic cleansing of the temple were prompted to confess faith in Jesus for selfish reasons. The omniscient Lord saw through these false believers and refused to trust Himself into their circle. Human nature can be so twisted by sin that it will even manipulate the goodness of God for selfish purposes.

Took: What can you do to protect yourself from the daily attacks of your own selfish human nature? How would you recognize genuine faith in a person?