The decree of God is His purpose or determination with respect to future things. We have used the singular number as Scripture does (Romans 8:28; Ephesians 3:11), because there was only one act of His infinite mind about future things. But we speak as if there had been many, because our minds are only capable of thinking of successive revolutions, as thoughts and occasions arise, or in reference to the various objects of His decree, which being many seem to us to require a distinct purpose for each one. But an infinite understanding does not proceed by steps, from one stage to another: “Known unto God are all His works from the beginning of the world” (Acts 15:18).
– Pink, Arthur W.; The Attributes of God; Kindle Edition; page 10