There is some confusion here. Asking Less Wrong flavored questions using theological terms generally requires misusing the terms. This is unfortunate, because these questions are really interesting, but most us don't have the requisite understanding of theology to do it well (including myself obviously(although, I venture that I might know more than most(#nesting))). So, my answer will be really disappointing.

In the monotheistic theology of Islam (represented by Al-Farabi), Judaism (represented by Maimonides), and, Christianity (represented by Thomas Aquinas), when it is said that God is omnipotent, they are saying God is not lacking in power, not that God can actually will to do any particular action whatsoever. In this way God is restrained. For example, God cannot create a rock so heavy that he cannot lift it because that is not a logical possibility. Or as a mathematician once said, "Nonsense is nonsense, even if you say it about God."

To your question about a loving God's possibility to deceive. This is a tough question because it is several in one. Can God deceive, can God's nature be learned about through observation of the created universe, and can God deceive about his nature? The first two questions are contested within each faith tradition, the third question (which I think is most relevant here) third is not disputed by the three philosophers. They all would say, "No."

I'm going to summarize a really long arguments the best I can: since God is a self-caused simple being (having no parts and lacking in no quality), his intellect (it's an operation) can only be directed toward Truth and his will (it's his other operation) can only be directed toward the Good (which is love).

This argument requires that we agree that Truth and Goodness have a primary level of existence, whereas falsity and evil exist contingently on the existence of truth and goodness. Since God has no parts, he cannot be oriented towards the composite essences of falsity and evil.

This is definitely an unsatisfying solution for most of us. The major problem for us approaching Theological Epistemology, as I see it, is that we have to start by explaining what metaphysics we are willing to accept and what we aren't.