The general and abstract concept of God shared by theist and nontheist alike is one in which He is supreme, head honcho of the universe, all-powerful, all-knowing, etc. Even atheists reject belief in such an entity, however conceived; their arguments generally do not refute a deus otiosus but rather the complexus of a Platonic theos, the Elohim of Jewish Scripture, the God of traditional Christianity, etc. Tillich/Spong style theology suggests that this concept is inadequate to explain exactly what God is.
So does Trinitarian theology.
The one thing omniscience cannot know is what it feels like to be in doubt, to worry about what might happen, to doubt.
If humility is a virtue, it is one that cannot be shared by a supreme being.
If self-sacrificing love is the highest of virtues, then how, in the absence of a universe, can an entity by itself choose to do so, and under what (self-imposed) rules can it make a sacrifice of itself?
The entire point to the Trinity is that God is not just Up There and All-Powerful, but also found in the person of a man who walked the earth as one of us, who felt doubt (“Eloi, eloi, lama sabachthani”) and grief (“Jesus wept”) – whose will was capable of being opposed to the divine will and of choosing to make a self-sacrifice in order to follow the divine will (“If you are willing, take this cup from me. Nevertheless, not my will but yours be done.”)
God knows what we go through, our hopes, our fears, our dreams, our nightmares, our tenderness, our anger, our lust, our grief. He’s been there, done that.
Picturing Jesus as Omnipotence wearing a human body like a suite of clothes pleases some conservative Christians out of their love for Him. But it’s not the Scriptural picture. He loved and grieved and felt anger and sorrow and worry and tiredness, just like any of us.