God is Love
In the course of its history, Israel was able to discover that God had only one reason to reveal himself to them, a single motive for choosing them from among all peoples as his special possession: his sheer gratuitous love. And thanks to the prophets Israel understood that it was again out of love that God never stopped saving them and pardoning their unfaithfulness and sins.
Source: Catechism of the Catholic Church (Vatican.va)