Here, sowing to the flesh means pandering to the flesh’s evil desires. Corruption is the word meaning degeneration, as in decaying food. Sin always corrupts and, when left unchecked, always makes a person progressively worse in character.
Commentary from the MacArthur study Bible, notes for Galatians 6:8.

This expression describes not only a life that endures forever but, primarily, the highest quality of living that one can experience.
Commentary from the MacArthur study Bible, notes for Galatians 6:8.
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