Sadly the answer to that question is no! We are all God’s creation, but we are not all his children.

The good news is anybody can become one of God’s children through adoption.

I have heard many people say that we are all God’s children, but that is not biblical.  Some people say this just out of a warm belief and something they picked up out of Hollywood movies.

Unfortunately this belief has led some down a path where they accept more things that are not true.

For example some will use this as an argument against the doctrine of hell. They will ask “would a good God would throw his children in Hell? The answer is simple no he does not throw any of his children in hell, but we are not all his children.

The Mormons will take a different twist and say we were all God’s spirit children in heaven before we came to this earth. They even declare that Jesus and Satan were brothers and Jesus was our elder brother during this time. That answer that false belief is a little more complex.

When God created (Gen. 1:1) all alone by himself (IS 44:24) he created Lucifer (Ezek:28:13) apart from him nothing came into being (John 1:3) This includes everything in heavens or on earth whether visible or invisible. All things were created by him.

Examining these scriptures we see Lucifer is a fallen angel who was created by God/Jesus. He did this all alone by himself. Since Jesus created Lucifer it is not logical or scriptural to say that he is the literal brother of his own creation. This is not the Jesus of the bible. Unfortunately believing in a false Christ will also cause a person to die in their sins John 8:24

Now let’s look at some scripture that shows us we are not all God’s children.

John 8:42-44

42        Jesus said to them, "If God were your Father, you would love Me; for I proceeded forth and have come from God, for I have not even come on My own initiative, but He sent Me.

43        "Why do you not understand what I am saying? It is because you cannot hear My word.

44        "You are of your father the devil, and you want to do the desires of your father. He was a murderer from the beginning, and does not stand in the truth, because there is no truth in him. Whenever he speaks a lie, he speaks from his own nature; for he is a liar, and the father of lies.

The Pharisees were very religious people who claimed God was their Father and Jesus rejected that idea. Jesus said their Father was the devil. Why would Jesus say that if we really are all God’s children?

We can become the children of God through belief.

John 1:12 But as many as received Him, to them He gave the right to become children of God, even to those who believe in His name.

Now why would we need to become his children if we are all already his children?

Gal 4:3-7

3          So also we, while we were children, were held in bondage under the elemental things of the world.

4          But when the fulness of the time came, God sent forth His Son, born of a woman, born under the Law,

5          in order that He might redeem those who were under the Law, that we might receive the adoption as sons.

6          And because you are sons, God has sent forth the Spirit of His Son into our hearts, crying, "Abba! Father!"

7          Therefore you are no longer a slave, but a son; and if a son, then an heir through God.

(NAS)  (see also Rom. 8:15-23)

Nobody adopts their own children. They adopt those who were not born their children but become legal children or heirs after adoption.

Hollywood movies and warm feelings of us all being Gods children might feel nice. However this false belief can in the end cause great harm,

Robert Kiser is the author of a few free pdf books and the . 
Roberts books explains and defends the Christian Faith. His book also includes a section on Cults including Mormonism and Jehovah Witnesses. https://archive.org/details/@robert_kiser