We all believe in our hearts . . . that there is a single and simple spiritual being, whom we call God . . . .
(Belgic Confession, Article 1, The Only God)
. . . God put [Christ Jesus] forward as a propitiation by his blood . . . to show God's righteousness, because in his divine forbearance he had passed over former sins. It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus. (Romans 3:25-26 ESV)God’s saving love did not cancel out his justice, but rather, from his love, he designed a plan to save sinners in a just way. Christ’s death was a propitiation—a way for God to express the wrath against sin that his justice required. The sinner’s own sin was counted as Christ’s, and Christ bore God’s wrath in our place, so God could be both “just and the justifier of the one who has faith.” This one act of God demonstrated both attributes—his love and his justice—and they worked in perfect harmony.
Divine simplicity has implications for our study of God. We’ve already mentioned one: Since God is simple, we can’t emphasize one attribute over others or consider one attribute more true to the nature of God than others. That God is simple also means he is the same being with the same attributes throughout history. Anyone who thinks of him as full of wrath during Old Testament times and full of love from New Testament times onward has misunderstood him1. In every time period, all of God’s actions are consistent with all of his attributes. Finally, if God is simple, he can’t limit or set aside any of his attributes, even temporarily. All of his attributes are identical with his being—they are what he is as God—and he can’t limit one without ceasing to be God. 2
1] Wayne Grudem, Systematic Theology, p. 180.
2] Michael Horton, The Christian Faith, p. 230].