When referring to the holiness of God, the definition takes on a much richer meaning. God's holiness is his defining characteristic. It's a term used in the Bible to describe both his goodness and his power. It is completely unique and utterly all-powerful, radiating from God like an energy. In fact, God's holiness is so overwhelming that it can actually be dangerous to approach.
Later on in the Bible, we see incredible stories of God's holiness expanding out from the temple and purifying things that were otherwise impure. Isaiah, for example, has a vision where he enters the temple impure but is purified by a burning coal—a physical embodiment of God's holiness. Later on, Ezekiel also has a vision where the holiness of God pours out from the temple like a river, revitalizing and purifying all the land it touches.
These examples of God's holiness purifying impure things all lead up to Jesus—God's holiness in human flesh. Jesus heals the sick, raises the dead, and casts out demons. All of these acts are examples of God's holiness purifying the things it comes into contact with.
Through all of these examples, we are able to piece together a compelling picture of the holiness of God. God's holiness is a powerful force that must be treated with the utmost respect. At the same time, God's holiness is a gift that can heal a broken and impure world. As followers of Jesus, a part of God's holiness now resides in us as well, and it’s our mission to go out and spread the holiness of God to all the world.