Why did God tell Adam and Eve not to eat from the tree of knowledge of good and evil?
God gave the command as a test of obedience. He placed Adam and Eve in the garden with one simple responsibility—not to eat from that one tree—to see whether they would remain obedient. The fruit itself was not described as wicked; the prohibition functioned as a means of testing, and Adam failed.
Les explains that God sovereignly set this arrangement in motion. He put Adam and Eve in the garden and gave them one simple responsibility: they were not to eat of that one tree. It was merely a means of testing to see if they could remain obedient. There was not anything especially wicked in the fruit itself; the tree served as a test. Adam flunked totally and ate. Because he sinned, a sovereign God declared that all his offspring would inherit that sin nature. This also explains why Adam's fall plunged the whole human race into that condition and why Christ had to die to bring fallen mankind back to Himself.