197 While nothing need be added to the one redemptive sacrifice of Christ, it remains true that our free refusal can prevent the heart of Christ from spreading the “waves of his infinite tenderness” in this world. Again, this is because the Lord wishes to respect our freedom. More than divine justice, it was the fact that Christ’s love might be refused that troubled the heart of Saint Therese, because for her, God’s justice is understood only in the light of his love. As we have seen, she contemplated all God’s perfections through his mercy, and thus saw them transfigured and resplendent with love. In her words, “even his justice (and perhaps this even more so than the others) seems to me clothed in love”.
Source: Dilexit Nos (Vatican.va)