From an article at Experimental Theology discussing the Christian Church’s problems with gay marriage and gentiles.

A key notion in Rogers’ book is that the vast majority of Christians need to recover their identity as Gentiles. This is important for a few different reasons. First, this recovery highlights the fact that we are not “by nature” children of God. We’ve been chosen and adopted. In the language of Paul we’ve been “grafted into” the tree of Israel. Second, this action of God, grafting in the Gentiles, highlights how the grace and election of God determines the people of God. We are not God’s children because of nature. We are God’s children because of election. This places election at the center of Christian notions of marriage (and celibacy) rather than a Darwinian focus on procreation. Marriage is grace, not biology. Finally, a recovery of our identity as Gentiles helps us understand why God’s actions toward the Gentiles was such a shock and offense to the Jews (both Christian and non-Christian). Importantly, this shock was very much focused on issues of holiness and morality.