Question: Why do Jews hang a Mezuzah on their doorpost?
The Torah gives us instructions for living - how to actualize our potential, how to have a successful marriage, how to raise healthy children, and how to find happiness, meaning and fulfillment. God's got it worked out to a science.
God told us to put the verses Deuteronomy 6:4-9 and 11:13-21 on our doorpost, to remind us of these "instructions for living" every time we pass through the doorway.
With blessings from Jerusalem,
Rabbi Shraga Simmons