Positive Mitzvah Two

To acknowledge the Oneness--complete Echad of G-d

Devarim 6:4 Shema' Yisrael: Hashem is our G-d, Hashem is One.

The sun shines, plants grow, people breathe, water flows and the wind blows. Each has its own way of functioning, yet they all draw power and energy from one source. This source is Hashem. This Positive Mitzvah commands us to believe that Hashem is the One and only power - the One and only G-d. In today's world only Yisrael recognizes Hashem as the One and Only, thus He is our G-d; but after the final Redemption, all the world will acknowledge that Hashem is One (Rashi)

The Mitzvah to believe in G-d's Unity is mentioned in many places, and the Sages also call it the Mitzvah to believe in the Malchut Shamayim (Kingdom of Heaven), for they speak of the obligation "to take upon oneself the yoke of the Kingdom of Heaven" (Berachot. 13d), that is to say, to declare G-d's Unity and to believe in Him.