God Is One

Know therefore this day, and consider it in thine heart, that the LORD he is God in heaven above, and upon the earth beneath: there is none else. (Deuteronomy 4:39 KJV)

Now look into it: into days long past, before your time — all the way back to the day God first created human beings on earth, from one end of heaven to the other. Has anything this amazing ever happened? Has anything like it ever been heard of before? Has any people ever listened to a god’s voice speaking out of fire, as each of you have, and survived? Or has any god ever tried to take one nation out of another nation using tests, miracles, wonders, war, a strong hand and outstretched arm, or awesome power like all that the Lord your God did for you in Egypt while you watched? You were shown these things so that you would know this: The Lord is the only God. There’s no other god except him. From heaven he made you hear his voice in order to discipline you. On earth he showed you his great fire. You heard his words from that very fire. And because he loved your ancestors and chose their descendants after them, God brought you out of Egypt with his own presence, by his own great power, in order to remove larger and stronger nations from before you and bring you into their land, giving it to you as an inheritance. That’s where things stand right now. Know then today and keep in mind that the Lord is the only God in heaven above or on earth below. There is no other. Keep the Lord’s regulations and his commandments. I’m commanding them to you today for your well-being and for the well-being of your children after you, so that you may extend your time on the fertile land that the Lord your God is giving you forever. (Deuteronomy 4:32-40 CEB)

Chosen by God, therefore we must know, believe and understand Him.
"You are my witnesses," declares the LORD, "and my servant whom I have chosen, that you may know and believe me and understand that I am he. Before me no god was formed, nor shall there be any after me. I, I am the LORD, and besides me there is no savior. I declared and saved and proclaimed, when there was no strange god among you; and you are my witnesses," declares the LORD, "and I am God. Also henceforth I am he; there is none who can deliver from my hand; I work, and who can turn it back?" (Isaiah 43:10-13 ESV)

For thus says the LORD, who created the heavens (he is God!), who formed the earth and made it (he established it; he did not create it empty, he formed it to be inhabited!): "I am the LORD, and there is no other. I did not speak in secret, in a land of darkness; I did not say to the offspring of Jacob, 'Seek me in vain.' I the LORD speak the truth; I declare what is right. (Isaiah 45:18-19 ESV)