Taken from writings on Genesis 3

Obedience that may not be tested is no obedience at all. Here the question is simply one of God’s authority, and of man’s ready subjection to Him. The test was a perfect one. Had God made it to be in some question of moral evil, such would not have so distinctly asserted the authority of God. But here the partaking of the fruit was only evil, because God had forbidden it. There was no reason why the fruit should not be eaten, other than the plain command of God. Many now likewise judge of obedience after the flesh likewise. They can see some reason why they should live honestly; but such commands as relate to Baptism or the Supper of the Lord, for instance, are stigmatized as unnecessary. There is no real perception of God, and of His will being supreme, in such cases.