We all like to pick and choose. When we're at a diner and it comes time to order, my wife braces herself for the process:
"Ummmm...Can I have the_________," I ask.
"Sure," says the waiter, writing the order.
"But can I have _________ with it instead of_____?"
"Sure," writing some more.
"Oh and can you ask them to use non-stick spray instead of butter?"
"Uh, we don't have that..."
"Oh, that's fine, that's fine."
By this time, my wife's head is deep in her palms and she has slid half way under the table.
One some level, we all like to pick and choose. And, if we're honest, on some level we pick and choose which of parts of the Gospel we're careful to keep. We say things like "I can't help it; that's just how I am," or "that's how I do it." We might watch our language, but we're kind of shady about money. We keep our bodies pure, but are utterly cruel with our words. We like performing good works, but neglect prayer (or vice-versa). We enthusiastically teach a Sunday School lesson and then turn into a nasty piece of ice when we get home.
But God wants to transform our whole person. Thus, St. Nicholas Cabasilas writes,
If we share in His blood, we must share in His will. We cannot be joined to him in some ways, and yet be separated from Him in others, neither can we love Him in one way and be hostile to him in another, nor be His children on the one hand and worthy of blame on the other. Nor yet can we be his members, but be at the same time dead ones for whom it avails nothing to be grafted into Him and be born anew. This would be like the branch which is severed from the true vine, whose end is to be cast out and to wither and to be thrown on the fire.*
*The Life in Christ, p.161