Adolf von Harnack, for example, wrote a book translated into English as What Is Christianity? Harnack argued that the essence of Christianity is found in two principles, the universal fatherhood of God and the universal brotherhood of man. Ironically, those two principles are actually foreign to Christianity. God is not the father of everybody, except as their Creator. When the Scriptures speak of God's fatherhood, they describe a filial relationship that exists only between God and his redeemed children. Only those who are in Christ have the privilege of addressing God as Father … it is so insidious when people talk about the universal fatherhood of God. It is an extraordinary privilege that we [Christians] can address the Creator of heaven and earth in terms of filial and personal intimacy … The Bible speaks of a universal neighborhood, not a universal brotherhood. That is, every person is my neighbor, but only fellow Christians are the adopted children of God.