It is the holiness of God that defines His character, and all of His other characteristics. This holiness is what sets Him apart from His creation and what makes Him completely unique from anything and everything else.
It is this understanding that He is transcendent or set apart from His creation, that we must keep in view as we explore all the other attributes that make God who He is; it is literally the starting point for or understanding of His person.
While all of the attributes of God are woven together so that none can be taken without all of them falling apart, it is His holiness that bonds them together. This is the reason that when given that view of angels around the throne in Isaiah 6, they are crying that He is "holy, holy, holy". It is the holiness of God that manifests itself in the actions that He takes in the world such as His mercy, righteousness, and judgment.
If the holiness of God is what He is, then we could say that the love of God is who He is.
It is His love that defines who He is, as the love existed in perfection in that before there was a creation from which to be holy and set apart. This is what John means to convey when He says that, "God is love" (1 John 4:16), it is who He is and has always been.
This understanding of love will help frame our theological view of the purposes and moves of God in redemption.
God did not send His Son so He could love us, but because He did love us. (John 3:16)
Why does God love us? Because it is who He is.
It is by this attribute, God allows us to understand His demeanor and actions in the world. While they are manifestations of holiness they are springing from the root of His love.
It is for these reasons that the love of God and the holiness of God cannot be seen separately, or pulled apart from one another. If we view Him through the lens of love alone, or through the lens of holiness alone, we will come away with a warped understanding of the theology of God. One could even argue that most of the misunderstandings, and indeed, false beliefs of God are due to an over-emphasis of one of these attributes over another.
Luther's statement of, "Crux Probat Omnia", or "the cross proved everything" is applicable to our understanding of the holiness and the love of God. We can best understand the relationship between the two here, as God's judgment upon sin and all the is unholy, embraces with His mercy and love in the person of His Son.
Any attempt to view either of attributes as standing alone, or separated from one another is to rob ourselves of the gospel of God. It would steal away the understanding of His moves in creation and history, and leave us hopeless and most miserable.