The sin of Adam was a rejection of what he was created and given to be by his Father in heaven—thus a rejection of the Father Himself, as well as His Word and Spirit.
“In the day that you eat of it you will surely die.” They did. We do.
You can make fun of “Father Knows Best” all you want. But He does [know best]. So the Word, His only begotten Son, became flesh—human flesh--distinctly male flesh—to do the will of His Father that Adam and every man since has failed to do. And He did it not by man’s will, but by His Father’s. On the way to the cross He prayed, “Not My will but Thy will be done.”
To hear and/or the entire sermon preached for the Eighth Sunday after Trinity, click on this link. http://lcmssermons.com/index.php?sn=3374