How the Law Applies 1
Gal 4:28,29 Now you, brothers, like Isaac, are children of promise. At that time the son born in the ordinary way persecuted the son born by the power of the Spirit. It is the same now.
One of the primary identifying marks distinguishing children of God from children of the devil is that children of God love their fellow Christians, but children of the devil hate them. ( 1John 3:10,15) So “Do not be surprised, my brothers, if the world hates you. We know that we have passed from death to life, because we love our brothers. Anyone who does not love remains in death.” 1John 3:13,14
This is particularly the case concerning those of a superficial religious origin. Back then it was the zealous unbelieving Jews persecuting the Christians (which I remind you was compose of those who believe in Christ - both Jews and Gentiles). Today this is largely played out in the Muslim's persecution of Christians, particularly in the Third World - The sons of Ishmael (Muslims) persecuting the sons of Isaac (Christians).