Yale's Miroslav Volf has a 17 December 2015 piece entitled Wheaton professor’s suspension is about anti-Muslim bigotry, not theology. It is a sloppy piece of mere journalism but it does raise an important question:
What is theologically wrong with asserting that Christians and Muslims worship the same God, according to Hawkins’s opponents — and mine? Muslims deny the Trinity and incarnation, and, therefore, the Christian God and Muslim God cannot be the same. But the conclusion doesn’t square. And Christians, though historically not friendly to either Judaism or the Jews, have rightly resisted that line of thinking when it comes to the God of Israel.
The important question is this: Is someone who denies that the Christian and Muslim Gods are the same logically committed to denying that the Christian and Jewish Gods are the same? Volf seems to think so. To the extent that an argument can be attributed to Volf it seems to be this:
A. There are good reasons to deny that the Christian and Muslim Gods are the same if and only if there are good reasons to deny that the Jewish and Christian Gods are the same.
B. There are no good reasons to deny that the Jewish and Christian Gods are the same.
C. There are no good reasons to deny that the Christian and Muslims Gods are the same.
I think one can reasonably reject (A). Volf writes,
For centuries, a great many Orthodox Jews have strenuously objected to those same Christian convictions: Christians are idolaters because they worship a human being, Jesus Christ, and Christians are polytheists because they worship “Father, Son and the Spirit” rather than the one true God of Israel.
It is arguable however that these great many Orthodox Jews have misrepresented the Christian convictions. Christians do not worship a mere human being; they worship a being that is both human and divine. So the charge of idolatry is easily turned aside. And Christians are not polytheists since they explicitly maintain that there is exactly one God, albeit in three divine persons. Trinitarianism is not tri-theism.
A Christian could say this: The God of the ancient Jews and the God of the Christians is the same God; it is just that his attributes were more fully revealed in the Christian revelation. The Christian revelation augments and supersedes the Jewish revelation without contradicting it. Or did Jews before Christianity arose explicitly maintain that God could not be triune? Did they address this question explicitly? And did they explicitly maintain that Incarnation as Christians understand it is impossible? (These are not rhetorical questions; I am really asking!) Suppose the answers are No and No. Then one could argue that the Christian revelation fills in the Jewish revelation without contradicting it and that the two putatively distinct Gods are the same. My knowledge of an object can be enriched over time without prejudice to its remaining numerically one and the same object.
Analogy: the more Dale Tuggy 'reveals' about himself, the fuller my knowledge of him becomes. Time was when I didn't know which state he hails from. At that time he was to my mind indeterminate with respect to the property of being from Texas: he was to my mind neither from Texas nor not from Texas. I simply had no belief about his native state. But now I know he is from Texas. There was no real change in him in this respect; there was a doxastic change in me. My knowledge of the man was enriched due to his 'self-revelation.'
Now why couldn't it be like that with respect to the O.T. God and the N.T. God? We know him better now because we know him through Jesus Christ, but he is numerically the same One as we knew before.
It is different with Islam. It is arguably a Christian heresy that explicitly denies Trinity and Incarnation which (from the Christian point of view) are attributes God has revealed to us. Islam takes a backward step. Arguably, Islam's God does not exist since it is determined explicitly to be non-triune and non-incarnated. The God of the O. T. was not explicitly determined to be non-triune and non-incarnated; so there is no difficulty with the O.T. God being identical to the N. T. God. But what if Jews now claim, or even before the Christ event claimed, that their God is non-triune and non-incarnated? Then their God does not exist. This seems like a reasonable line for a Christian to take. It involves no bigotry whatsoever.
Of course, these issues are exceedingly difficult and one cannot reasonably expect to reach any agreement on them among learned and sincere truth-seekers. I am not being dogmatic above. As before, I am urging caution and rejecting simple-minded solutions. Volf's simple-mindedness and sloppy journalism gets us nowhere. And his accusations of bigotry are deeply offensive and themselves an expression of politically correct bigotry.