The verse that most directly speaks about the depth of God's love for us is Ephesians 3:18, which says: "may have strength to comprehend with all the saints what is the breadth and length and height and depth of Christ’s love" (Ephesians 3:18). This verse emphasizes that God's love for us is vast in every dimension—wide, long, high, and deep—beyond full human understanding. It highlights the immeasurable and all-encompassing nature of God's love for believers, encouraging them to grasp its greatness together with all God's holy people. This love is described not only as deep but also eternal, sacrificial, and reaching us in our undeserving state, as shown through Jesus Christ's sacrifice (Romans 5:6-10, Isaiah 53) and the cost of that love (Ephesians 5:1-2).
In summary, the depth of God's love is scripturally described as boundless and incomprehensible, underpinned by the sacrifice of Christ and reaching even the lowest and most undeserving places in humanity.