Do all children who die go to Heaven?

Although Romans 5:12 demonstrates that all mankind is born with a sin nature which, naturally, is a statement inclusive of children, the Bible demonstrates there is a time when a child doesn't know right from wrong.

Deuteronomy 1:39: Moreover your little ones, which ye said should be a prey, and your children, which in that day had no knowledge between good and evil, they shall go in thither, and unto them will I give it, and they shall possess it.

Isaiah 7:16: For before the child shall know to refuse the evil, and choose the good, the land that thou abhorrest shall be forsaken of both her kings.

God is a just and righteous God. As such, any child who dies, prior to reaching a point in their life where they knowingly make a choice to disobey God's will for their life and His commandments, is innocent of any wrongdoing.

John 9:41: Jesus said unto them, If ye were blind, ye should have no sin: but now ye say, We see; therefore your sin remaineth.

For the reasons stated above, I believe we can be confident that any child who dies in his or her innocence immediately goes to Heaven to reside forever with the Lord Jesus Christ.