We discuss John Piper's sermon: TULIP, Part 1 of 9: 
Introduction
A Seminar for The Bethlehem Institute
March 7, 2008 | by John Piper | Topic: The Doctrines of Grace / Calvinism

John Piper introduces his 9 part series on the topic of Calvinism with this quote from AW Tozer.

"It is my opinion that the Christian conception of God current in these middle years of the 20th century is so decadent as to be utterly beneath the dignity of the Most High God and actually to constitute for professed believers something amounting to a moral calamity. All the problems of heaven and earth, though they were to confront us together and at once, would be nothing compared with the overwhelming problem of God: That He is; what He is like; and what we as moral being must do about Him.  The man who comes to a right belief about God is relieved of 10,000 temporal problems, for he sees at once that these have to do with matters that at the most cannot concern him for very long… Low views of God destroy the gospel for all who hold them…"

Here is other quotes from Tozer, not presented by Piper but relevant nontheless: 

"God sovereignly decreed that man should be free to exercise moral choice, and man from the beginning has fulfilled that decree by making his choice between good and evil. When he chooses to do evil, he does not thereby countervail the sovereign will of God but fulfills it, inasmuch as the eternal decree decided not which choice the man should make but that he should be free to make it. If in His absolute freedom God has willed to give man limited freedom, who is there to stay His hand or say, 'What doest thou?' Man’s will is free because God is sovereign. A God less than sovereign could not bestow moral freedom upon His creatures. He would be afraid to do so."

- A.W. Tozer, The Knowledge of the Holy: The Attributes of God

Another quote, from a non-Calvinist:

The providence of God…is present with, and presides over, all things; and all things, according to their essences, quantities, qualities, relations, actions, passions, places, times, stations and habits, are subject to its governance, conservation, and direction. I except neither particular, sublunary, vile, nor contingent things, not even the free wills of men or of angels, either good or evil: And, what is still more, I do not take away from the government of the divine providence even sins themselves, whether we take into our consideration their commencement, their progress, or their termination…To the essence of God no attribute can be added, whether distinguished from it in reality, by relation, or by a mere conception of the mind; but only a mode of pre-eminence can be attributed to it, according to which it is understood to comprise within itself and to exceed all the perfections of all things. This mode may be declared in this one expression: "The divine essence is uncaused and without commencement." Hence, it follows that this essence is infinite; from this, that it is eternal and immeasurable; and, lastly, that it is unchangeable, impassable and incorruptible…Arminius

Piper begins his sermon with a quote from Tozer about the idolatry of believing something lessor about God than He truly is, and the irony is the Tozer himself saw the Calvinistic explanation of God as lessor.