"Come here, John. John, come here. John. JOHN, COME HERE!!!"
John does not always obey us quickly (or at all). Sometimes, of course, he will do what we ask -- stop touching the CDs; give the pen to Mama; stop hitting Mama with the truck.
But when I give him an order and he does not obey me, then I know that the times he obeys are not because he has an obedient spirit -- it's because what I'm asking him is not too onerous, in his mind. Perhaps it's what he wants to do anyway. So 50% obedience (I'm being generous here) is, to me, no obedience at all, because it only takes one incident of disobedience for me to know that John thinks he knows better than I do what is best for him to do.
I used to think it was unfair for the Bible to say that whoever breaks one little part of the law is guilty of breaking it all (James 2:10; see also Matt. 5:19). Now that I have a child, I am reminded every day that if I'm not rebelling against God at this moment it's just because what he requires of me is not too onerous, in my mind; or, sometimes, I obey because I choose to believe that God knows better than I do. Sometimes, though, I do still disobey, and now I see that my sin is as great as if I had broken every one of God's commands.
Fortunately he is in the business of loving and redeeming rebellious souls. "While we were enemies, Christ died for us" (Rom. 5:8).