The concept of who is a "child of God" depends on the specific religious tradition you're asking about.
* In Judaism: Moses is considered the most important prophet, lawgiver, and leader. While Jewish tradition speaks of a special relationship between God and the people of Israel, and sometimes uses familial language metaphorically, the idea of a specific individual like Moses being a "child of God" in a literal sense isn't a central concept. He is seen as God's servant and messenger.
* In Christianity: Christians believe that Jesus Christ is the unique Son of God. While other individuals can be considered children of God through faith and adoption into God's family (especially through baptism), Moses is primarily seen as a great prophet and figure of the Old Testament, not as a "child of God" in the same way as Jesus.
* In Islam: Moses (Musa) is a revered prophet in Islam. Muslims believe that God is one and has no offspring. Therefore, no human, including prophets like Moses, are considered "children of God" in a literal sense. They are servants and messengers of God.
* General Usage: The phrase "child of God" is often used more broadly to describe anyone who follows God's will or possesses qualities associated with divine goodness. In this sense, one could argue that Moses's dedication to God's law would qualify him as a child of God.
In short, while Moses is a highly respected and important figure in all three Abrahamic religions, whether he's considered a "child of God" depends on the specific theological understanding of that term. It's most clearly applicable in a Christian context, but even there, the term is usually reserved for those who have a personal relationship with Jesus.