Reading McMurrin's comparative historical analysis of Christian theology (see reference below) was fascinating in many ways - one of which was relating to the Omnipotence attributed to God.
It is clear that having a God who can do anything instantly and directly and without any restrictions leads to serious theological problems: the most serious of which is 'the problem of pain' - in particular the problem of the extremity of human suffering.
The original act of creation can be believed to be good and charitable; it is credible that the Almighty God should deign to create beings to share His Joy. It is credible that He should deign to increase their Joy by creating them with the power of free will so that their joy should be voluntary. It is certain that if they have the power of choosing Joy in Him they must have the power of choosing the opposite of Joy in Him. But it is not credible that a finite choice ought to result in an infinite distress...
From What the Cross Means to Me, by Charles Williams.
In this essay, I think that William's is pointing out that while it seems reasonable and right that Men should suffer, there seems no reason - if God is both omnipotent and Good - why some Men should suffer so much.
Many people feel that if God can do anything, yet allows extreme suffering, that such a God is not Good.
And if God is not Good, then He is not God - therefore they do not believe in God.
But if God is wholly Good but not omnipotent, if God's power to effect Good is great but not complete - then this problem loses its force. Such a God is doing His best, but constrained by the reality of the situation.
This is, to a common sense reading, precisely the depiction of the Old Testament God. What seems to be described is a person who is always striving for Good but is constrained by the situation - in particular by the free choice of his people which can be influenced but not compelled; but also by time, and having to work in the material world.
While a few specific verses can be interpreted as, perhaps, implying omnipotence - this is certainly not the impression given overall - is it? The Old Testament God is a personality who does not make things happen except via the things of the world - and it is a reasonable inference that this God cannot make things happen except via the things of the world.
So, the bleg is this: what is the truly compelling evidence that God is specifically omnipotent - rather than ('merely') extremely powerful.
My suspicion is that the evidence is metaphysical, rather than scriptural - something we say God 'must be', something we assume a priori, rather than something we have been told by revelation.
My guess (from reading McMurrin) is that omnipotence is an attribute, a metaphysical assumption, derived from Classical Philosophy and read back into Christianity (and Judaism).
I don't imagine that Abraham, Isaac and Jacob would have assumed that God was omnipotent in the abstract later sense of instantly and directly being able to do anything at all; but rather that their God was extremely powerful, indeed by far the most powerful of all entities in reality (i.e. the most powerful of the 'gods' - i.e. of supernatural beings).
(I suppose A,I & J would not want to discuss the limits of God's power - just as one would avoid discussing the limits of his power with an absolute monarch. But neither did they seem to assume anything along the lines that everything could be set perfectly right in the world by God's instantaneously-active will re-arranging the nature of reality. That God worked through the world, constrained by the world, seems integral to the relationship between God and the Prophets and seems to be embedded in the very nature of the Old Testament.)
So, could it be that the apparently insoluble 'problem of pain' is a consequence of the abstract extremism of the concept of omnipotence: a concept which is both alien to common sense, and also fundamentally incomprehensible - something that can be described, but not felt from the inside.
The problem of pain is therefore perhaps insoluble only because omnipotence is humanly-meaningless - an unnecessary, and later-added philosophical abstraction through which we later Christians are insisting upon trying to interpret Christianity.
Yet maybe real, living Christianity never has regarded God in this way - because for us to Love God and have a relationship with him in time and mortality, excludes the deadly abstraction of omnipotence.
Note added: Omnipotence is an aspect of the monistic world view - but not necessary in a pluralistic world view (as comes through in William James philosophy). If we assume that ultimate reality contains more than one thing, it contains God and 'stuff'-that-is-not-God. Nothing is more powerful than God, but there is (and always was) other stuff. Neither God nor stuff can be destroyed - both are everlasting. In a pluralistic metaphysic, God did not create from nothing (ex nihilo) but using the stuff which was coexistent with God. Therefore, God must sometimes achieve his goals via using the stuff - that is, God is constrained by the stuff. Such a metaphysic fits comfortably with the Old Testament, seems indeed naturally to follow from it; and the OT reveals to us the nature of God the Father and the history of his relationship with his People. Therefore, since the Bible is a unity, the pluralistic metaphysic is compatible with the New Testament. "With God all things are possible" thus can be taken to refer to aims, not mechanisms: to God all ends are possible, but the means by which they are attained are under constraint. Hence the linear, narrative structure of the Old Testament - uncontroversially, God works via stuff, and without violation of the free will of Men and Angels - but to the pluraristic metaphysic this indirect and time-bound method is by necessity, not by God's restraint from deploying instantaneous and direct action to attain his goals. Hence God's miracles are done via stuff and on a timescale; not by instant transformation of stuff.