WHEN GOD REPENTS (or not)
Gen.6:6 And it repented the LORD that he had made man on the earth, and it grieved him at his heart.
The God Who had made the earth and its elements was about to destroy the earth by its elements. It had become corrupt beyond the limits of His longsuffering, a frightful status to be avoided at all costs. When the patience of God with sinners comes to an end, His wrath arises to a sudden destruction and there is no remedy (2 Ch.36:16 c/w Pro.29:1). As touching the elect, God is "longsuffering to us-ward, not willing that any should perish, but that all should come to repentance" (2 Pe.3:9), but branches in Christ that continually bear not fruit (like repentance) are liable to be taken away (Joh.15:2). They but cumber the ground (Luk.13:6-9), robbing productive specimens of valuable nutrients and are liable to spread their blight to them.
A principle reason for the Flood was "that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually" (Gen.6:5). Though the Flood purged away active sin and gave mankind a fresh start, its intense judgment in no way changed man's nature. After the Flood, God observed that "the imagination of man's heart is evil from his youth" (Gen.8:21). Fallen man's nature is so inherently corrupt that when shown favor he will not learn righteousness (Isa.26:10), nor will his nature be changed by ferocious judgment. See also Rev.16:9-21. The tree must be made good by God's grace before it can produce good fruit (Mat.7:18 c/w Mat.12:33). The fruit of the Spirit (e.g. faith) is the proof of a new nature, not the means of the new nature (Gal.5:22-23 c/w 1 Co.12:3 c/w Rom.8:14).
The situation was so bad with men that God repented that He had made (created) man. That saints might better appreciate the redeeming work of the new creation and glorify Jesus Christ for the covenant of grace, consider Matthew Henry's insight here: "God repented that he had made man; but we never find him repenting that he redeemed man (though that was a work of much greater expense), because special and effectual grace is given to secure the great ends of redemption; so that those gifts and callings are without repentance, Rom.11:29." Where sin abounded, grace did much more abound (Rom.6:20).