I would say the soul would be more than the engine. The soul would be like the computer system that coordinates everything, from the smog device to the fuel injection system to the brakes.
Dallas WillardThink of the soul as the computer system that runs the whole thing. And then the spirit is the executive center. It's the faculty of choice. And then you want that faculty governed by the truth of God and the Spirit of God.
Dallas WillardWhat Paul is clearly saying is that if anyone is worthy of being saved, they will be saved. At that point many Christians get very anxious, saying that absolutely no one is worthy of being saved. The implication of that is that a person can be almost totally good, but miss the message about Jesus, and be sent to hell. What kind of a God would do that? I am not going to stand in the way of anyone whom God wants to save. I am not going to say 'he can't save them.' I am happy for God to save anyone he wants in any way he can. It is possible for someone who does not know Jesus to be saved.
Dallas WillardHe [Peter after the resurrection] now understood that he and the church were to exercise a transcendent power that did not depend upon having a kingdom or government in any human sense, for it was literally a "God government" in which they were participants (Acts 1:6-8).
Dallas Willard