Ronald Hanko
In books of theology, you will sometimes read of an attribute called God’s simplicity. The word is confusing, and since it is not found in Scripture, it might be better to use a different word—perhaps perfection. God’s simplicity is part of His oneness; He is one in all of His attributes and works. There is no disharmony, no conflict, no contradiction among His works or attributes. They are all one. God is perfect and without weakness or flaw in any way.
God’s perfection is taught especially in those passages that say God is love, is truth, is light (1 John 1:5; 1 John 4:8; 1 John 5:6). That He is light means that there is no room in Him for darkness. That He is love means that there is no possibility of anything in Him that would compromise His love. This also means that His attributes are not really separate characteristics. They are like the facets of a diamond that cannot be separated from each other. Each sparkles and shines with its own glory, yet all together they make up one precious diamond jewel. To separate them is to destroy them.
Consider God’s mercy. It is not only the pity He feels of us in the misery and bondage of our sins, but also the power by which He delivers us from that misery. It is not a mere desire to help us, but the help He actually gives. His mercy and omnipotence are perfectly one, never separated, never in conflict.
Think, too, of God’s love. God’s perfection or simplicity means that His love cannot be separated from His justice, His eternity, His omnipotence, or any of His other attributes.
God’s love is always just, never revealed except in the way of perfect justice. In other words, He never loves anyone except in the way of fulfilling the demands of His own justice by sending Christ to die in their place.
God’s love is always eternal. There is no such thing as a love of God that is only for the present but not from eternity to eternity. Those He loves He has always loved and always will love. So, too, is His love omnipotent (almighty). It is never an empty sentiment, but it is a power that makes us the proper objects of His love.
God’s perfection is one of the reasons we believe that God does not love everyone or show grace to everyone. That would be saying that there is a love or grace of God that is separated from His almighty power. It would be to say that there is a love and grace of God in conflict with His justice, holiness, and righteousness, for He would be showing love to those who are not and never will be righteous and holy in Christ.
What a blessing for believers to know the truth about God’s perfection! To know it is to realize that His mercy is never in vain, His grace never unrequited, and His love never wasted.
(Ronald Hanko, Doctrine According to Godliness: A Primer of Reformed Doctrine [Jenison, MI: RFPA, 2012], pp. 56–57)