One attribute of an omni-God is omniscience. According to standard Christian doctrine, Jesus of Nazareth was God. If God is omniscient, then it seems to follow that Jesus was omniscient.
The problem is that this doesn’t seem to fit with various aspects of the canonical Gospels. For example, Jesus says only the Father knows something in particular, not the Son (Mark 13:32). Jesus increases in wisdom (Luke 2:40). He asks who touched his garments (Matthew 5:30). He asks where someone is (John 11:33). He doesn’t seem to know if something must happen (Matthew 26:43). More generally, if Jesus were omniscient, would he have been faking learning to speak Aramaic? Would he already have known carpentry? And so on.
This problem leads to various solutions. For examples,
1. Jesus was hiding his knowledge. (This might follow from the idea of the hidden Messiah, as seen in the Gospel of Mark, say.)
2. Jesus voluntarily gave up his omniscience upon becoming a man. (This solution has parallels to a solution to the problem of evil – that God voluntarily has given up some of his power in giving humans free will.)
3. Jesus wasn’t omniscient, but became omniscient after his ascension, say. (And perhaps was omniscient before his incarnation.)
4. The Gospel accounts are mistaken in the places that suggest Jesus wasn’t omniscient.
5. As God the Son and God the Father are different persons in the trinity, this means there might be things the Father knows that the Son doesn’t. (So, denying that an identity of essence translates into an identity of properties like omniscience.)
And so on.
What are we to say?
One point is that this is essentially a theology-led problem. That is, first assume a theological notion of the trinity and an omni-God. Only then do you really have a problem (how to reconcile these theological conceptions with what is presented in the Gospels).
Why does this matter? Because for some people, theologically created problems are an obstacle to entering into a relationship with God. That is, they say something like “This doesn’t make any sense, therefore Christianity and theism are nonsense.”
How can disputes such as the above be resolved?
I think a part of the answer is epistemic humility – Christianity is not a complete set theories about how God works, Jesus’ exact relationship to God the Father, and so on. Rather, it is a recognition that something important has happened. Now what do we make of it? In other words, it’s a process of trying to figure out things.
If one treats this basic stance as more primary, and theology, say, as secondary, then these sorts of problems (for example, how to reconcile the idea of God’s omniscience with the Gospels) become secondary (because they are essentially theology-led). They are put into context, whatever the exact theological resolution might be.
This isn’t to say the theology isn’t important. Of course the theological answers are important, and impact practice in a variety of ways. However, it is to say that these things are debated because they are debatable. It is probably not sensible to engage in internecine warfare on the basis of them. Rather, one can recognize there are a variety of responses, with a variety of strengths and weaknesses. One can build as best a case for a putative solution as one can.
(I.e., it seems many theological doctrines are probably a result of ‘theological overreach’. There is too much theory relative to evidence. There is a similar problem in various parts of science.)
A response to this might be: if dissension isn’t nipped in the bud, you’ll have fragmentation of the Church. With fragmentation, you’ll have some kind of undesirable chaos.
What is important for Christian Churches isn’t uniformity of theological doctrines, necessarily, but rather communication and innovation – one Church adopting practices, techniques, ideas, and so on, that work, from other Churches, refining them or adapting them to a different situation, and so on. At the same time this will have a tendency to resist pulling apart, just as communication and innovation leading to adopting words or pronunciations cause dialects to resist being pulled apart into different languages.