Let me share with you what the Book chobot halebabot says about the first Pasuk of the Shema Israel. SHEMA ISRAEL HASHEM ELOKENU HASHEM ECHAD. “Listen Oh Israel, HaShem is our God, HaShem is one”.

Most people believe that this verse refers only about the unity of God (ECHAD God is one). However, that is only one of the 3 principles of the Pasuk Shema Israel. We also learn two more things:

One, ELOKENU, Hashem is our God: we assert our condition of chosen people, which implies a special relationship with God. Not a relationship of favoritism and more rights for us but mainly, chosen for greater responsibilities. We have 613 obligations toward God, while the rest of the world only 7.

The next lesson is kind of hiding in the original Hebrew and then it appears in English or vernacular: “HASHEM is our God…” HASHEM is… means, HASHEM exists.
So Chobot haLebabot says that when we say the first Pasuk of the Shema Israel, and every time we see or kiss the Mezuzah which contains the Shema Israel, we should think about these 3 principles of our Jewish faith:

1. God exists.
2. We are His chosen people.
3. God is ONE

Mezuzah joke: http://www.aish.com/j/j/51477127.html.

Most people think that the Mezuzah cover is really the Mezuzah and the inside, just a parchment. Well, actually, the inside IS the Mezuzah and the outside is just a decorative/protective case also known as: BAYIT, or “house of the Mezuzah”.

If you really want to know what’s “inside a Mezuzah”, you’re actually asking: what is written in the Mezuzah?
The Mezuzah then, is a small handwritten scroll which contains the first two paragraphs of the Shema Israel.

Why it contains exclusively these two paragraphs? Because in both of them appears the Mitzvah of Mezuzah ukhtabatam al mezuzot betekha ubisharekha.

Similar to the Tefilin which contains 4 paragraphs (two of the Shema and two of Kadesh li) because in those 4 paragraphs the Mitzvah of Tefilin is mentioned.

Going back to the Mezuzah, the Shema Israel contains the basic principles of our faith, and by placing the Mezuza in our entrance doors we are asserting and remembering our beliefs every time we come in and go out.

For more Information watch this 30 seconds video: “Inside” a Mezuzah? http://www.youtube.com/watch?v=PACu3aosp1g