“Then the Lord saw that the wickedness of man was great in the earth, and that every intent of the thoughts of his heart was only evil continually.” Genesis 6:5.
How do we know what is good? The Bible tells us that God is good. In fact, it speaks of His goodness throughout Scripture.
“The Lord is good to those who wait for Him, to the soul who seeks Him. It is good that one should hope and wait quietly for the salvation of the Lord.” Lamentations 3:25-26.
“These six things the Lord hates, yes, seven are an abomination to Him: a proud look, a lying tongue, hands that shed innocent blood, a heart that devises wicked plans, feet that are swift in running to evil, a false witness who speaks lies, and one who sows discord among brethren.” Proverbs 6:16-19.