In helping to explain our human nature in comparison to the transformed nature that God calls us to, Kinlaw focuses a lot on the book of Mark. I wasn't aware of this but he comments that a lot of scholars and others historically haven't placed a whole lot of importance on the book of Mark, instead referring more to the other synoptics and NT books as being more power.
As I read the book, I was really drawn to the end of Mark 8. In The Message, chapters 30 - 38 are as follows:
... He then began explaining things to them: "It is necessary that the Son of Man proceed to an ordeal of suffering, be tried and found guilty by the elders, high priests, and religion scholars, be killed, and after three days rise up alive." He said this simply and clearly so they couldn't miss it.
But Peter grabbed him in protest. Turning and seeing his disciples wavering, wondering what to believe, Jesus confronted Peter. "Peter, get out of my way! Satan, get lost! You have no idea how God works."
Calling the crowd to join his disciples, he said, "Anyone who intends to come with me has to let me lead. You're not in the driver's seat; I am. Don't run from suffering; embrace it. Follow me and I'll show you how. Self-help is no help at all. Self-sacrifice is the way, my way, to saving yourself, your true self. What good would it do to get everything you want and lose you, the real you? What could you ever trade your soul for?
"If any of you are embarrassed over me and the way I'm leading you when you get around your fickle and unfocused friends, know that you'll be an even greater embarrassment to the Son of Man when he arrives in all the splendor of God, his Father, with an army of the holy angels."
For me, there's a lot of power in Jesus rebuking Peter for trying to pull Him away from what He knows must be His fate here on earth. Just as the Father had a plan for His son, God has a plan for each of us. Sometimes it isn't at all what we expect. Sometimes it can seem pretty painful even. Yet our calling is to indeed focus on where God leads us in our life, and not to turn back to self-reliance and the ways of contemporary culture. We are nothing without Him -- certainly not the Kingdom-builders and Kingdom-inheritors that He wants us to be. We can therefore, even embrace the difficult times in this life, full in faith and knowledge that they will not last and that the difficult times are important parts of our journeys to eternity.
In this scripture, God calls us to self-sacrifice with a focus on Him rather than on ourselves. It reminds me of my frequent admonition to myself to lose my "self" and focus instead on my life in Christ, allowing Him to live through me rather than the old and very human "me" to live through me.
Finally, in the end of Mark 8, Jesus makes it very clear what our marching orders are if we indeed are to spend eternity with Him. To me, this sums up our calling as Christians so clearly ... giving up our "selves," seeking and following God's plan for our lives, wherever that may lead us.