Many people today want to know the "one thing" that's important in their lives. They want to know their purpose. Jesus was similarly questioned about this "one thing" that we all must do.
"And one of the scribes came up and heard them disputing with one another, and seeing that he answered them well, asked him, “Which commandment is the most important of all?” Jesus answered, “The most important is, ‘Hear, O Israel: The Lord our God, the Lord is one. And you shall love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength.’ The second is this: ‘You shall love your neighbor as yourself.’ There is no other commandment greater than these." - Mark 12:28-30
What Jesus quoted was the Shema prayer, the most quoted, most central of all to the Jewish faith. So as Christians who do as Jesus does, we pay attention to this prayer and want to live it daily.
When you visit a Jewish home, upon entering, you will notice an object at the doorpost. This is a Mezuzah. It will look like our picture below except it's attached to the wall.
Look closely at the necklace above and you'll see a small glass vial, some inscriptions and a cross hung on a chain. Not everyone knows that it's also a Mezuzah.
The Mezuzah is special because it contains Scripture, the Word of God - in particular the Shema. This is what is inscribed inside:
The verse tells us that living a life in accordance with God's ways, brings blessings. To do just that we need to fix God's Words into our hearts and minds. We can meditate on Scripture, asking God how to apply it in our lives.
When people see us wearing the mezuzahs, they ask us about these and why we wear them. It's because we remember what's that one most important thing!