The ten other models are arranged in logical order from Semi-Deist and Process to Calvinist and Fatalist (in a very useful chart, 363-364). There is no way an average pastor will read this book from beginning to end, so I quickly located my own model under "The Openness Model (1)" in chapter 4. This includes the ideas of libertarian freedom (the power of contrary choice) and God taking risks (71, 78). God is not absolutely immutable, and his omniscience does not include "the future acts of free creatures" (71, 73, 79). But I was glad to see that even under this species there is a "range of sub-models" (74), as we find in Botany and Zoology. My own position seems to be close to the one he ascribes to Peter Baelz (75). "Love requires freedom" and "love creates in and for freedom" (Peter R. Baelz, Does God Answer Prayer? 1982, 26-26).
Then I tried to see how Tiessen's model (Middle Knowledge Calvinist) might free him from some aspects of Calvinism (232-270) that I can't swallow. He is still a Calvinist in believing that God "rules over creation in a sovereign and all powerful way" (290). As opposed to an Openness model, "God has surrendered none of his control" (291). "The whole history of creation has been determined by God in his eternal purpose" (338). There are other agents, self-determining creatures that do what they want to do but always within a context over which God maintains his sovereign prerogative" (291, 315). What he does not share is "John Calvin's aversion to the language of permission" (294). But permission is very helpfully explained "in the context of all that has gone before" (304, 310). This "leaves much room for the action of creatures without making them independent of God" (304). As a result Tiessen is confident "in the ability of God to effect his will through the non-coercive persuasion of spontaneously free agents" (306).
Obviously this solves a lot of problems, and it will make this modified Calvinistic model palatable to many. But the basic Calvinism remains. "Reformed theologians have clearly asserted that God's electing grace is unconditional. God does not elect people because of anything about them, including their faith, which he merely foresees; he chooses them in free and sovereign grace, and the faith he foresees is the faith he has chosen to give, from before the creation of the world" (346). That seems to imply that others are not elect, and people go into eternal damnation because God did not choose them. So I prefer to say that God loves every single person unconditionally, and no one is condemned, but we are chosen (predestined) to be free to enjoy his love or reject it (based on John 3:19-21, and as illustrated in C.S.Lewis' Great Divorce and The Chronicles of Narnia)
All Christians think that prayer is important and effective. What they disagree about is how it works in the mind of God. Tiessen's eleven species are only models that explain what theologians think is going on when we pray. I suspect most Calvinists pray much the same way as Arminians. What evangelicals squabble about is the explanatory model, not the experience of God's grace that they share.
How then do we settle which explanation is the correct one? Maybe none of us have got our minds around the infinite wisdom of God. Tiessen admits there is mystery and paradox (18). But theologians should explore and explain what they can.
He chides some students in his classes who are totally Arminian in saying that our salvation needs a free-will decision, but they are Calvinistic when they rejoice in the fact that God is "very much in control of the details of their lives" (13-14, 18). An acceptable model must be self-consistent. It should have "inner coherence and fit within one's overall theology (21).
For Christians the model will be biblical. That does not mean being based, or refuted, by a few proof texts. "One arrives at one's own understanding or model of God and his work in the world through a general impression drawn from the entire text of Scripture" (22). Tiessen thinks his own proposal "as the one that fulfills the demands of Scripture, experience and reason most satisfactorily" (25).
Thirdly we should be willing to consider other models that are proposed,
and this the author of this book has done superbly well. I am very impressed
by the richness of the recent evangelical theology that is brought together
in this book. There are no unpleasant, sarcastic, angry comments. And on
the back cover two of the five approving comments are from writers who
prefer the Openness model. Great commendation indeed.