People throughout history have left the confines of Christian dogma after honestly thinking about the problem of evil. In short, the problem of evil is a result of the idea that there is a God who is all-powerful (omnipotent), all-knowing (omniscient), and perfectly good, yet allows Satan to exist and influence people, allows children to die of cancer, baby fawns to burn to death in forest fires started by lightening, and allows about 80% of the all humanity to suffer in eternity in Hell. Over the centuries, there have been many attempts to justify the "evil" in the world. One such method is to deny that the Christian God of the Bible is actually omnipotent and/or omniscient. While the Bible clearly contains verses and stories that both confirm and deny omnipotence and omniscience as part of God's nature, and one can use the Bible to support virtually any position, philosophically speaking, if one is to accept that God is omnipotent, one must accept that he is also omniscient.
First we need to set some ground rules. For unbelievers, we are talking about imaginary concepts that have no real existence outside of our imaginations -- omnipotence, omniscience, and God. For believers, we must assume that the Christian Bible, especially the New Testament, provides us with truthful information about God. Therefore, when the Bible says, "With God all things are possible." (Matthew 19:26, Mark 10:27), we must accept that God's omnipotence is unlimited power, not just power that is in line with a being's "nature" or the laws of logic. Limitations have been suggested by theologians and those who try to get God of out of one or more philosophical pickles. If God wants to lie, we must accept that it is possible for God. If God wants to make a square circle, we must not be so arrogant in thinking that just because we can conceive of how that can be done, that it can't be done. Even today, quantum physics is showing us that what we interpret as the laws of logic don't always appear to apply in the quantum world. Omnipotence is unlimited power.
Ok, so what is power? In terms of a being, it is the ability to act. It does not matter if the being chooses to exercise its power or not; what does matter is the being's ability to exercise its power. A God who can smite, is just as powerful as a God who does smite.
Now onto omniscience, which is unlimited knowledge. We are talking about knowing everything -- past, present, and future. This is a requirement of omnipotence, and here is why: omnipotence is the ability to do (take some kind of action) anything, which includes the ability to share information. Sharing information requires prior knowledge of that information to be shared. In order to have the ability to share everything, you must know everything. To put it another way, for every piece of information you do not know, there is another thing you cannot do -- share that information.