The idea of God being omnicient / omnipotent confuses me

[ZeeJustin]

I'm an atheist, but I'd really like to understand more about what intelligent / rational believers actually believe.

I assume virtually all Christians, Jews, and Muslims believe that God is omnicient / omnipotent.

Does God have goals? motives? thoughts? plans?

If he has a goal, what is it?

I don't understand how humans could possibly be of any importance to God.

In the bible, there are several times where God puts people to tests. If he knows everything, what is the point of putting anyone to a test? He knows what the outcome will be.

If God created humans, why do they have sins? Doesn't this imply God is imperfect? Maybe it implies he doesn't want humans to be good beings. If so, why does Christianity assign such importance to humans over other animals?

Basically, I'm saying that if God is omnicient / omnipotent, what his creations do should be of no importance to them. They do what he wants them to do. There's no need for punishments or rewards or tests or anything.

I'm really hoping to get some answers other than "you have to have faith that we believe the right thing", or "it's his intention that these questions remain a mystery until after death." Those answers are just BS.

What is God capable of doing? Can he renounce his powers? I assume that God is not composed of matter. Could he manifest himself as a human being that dies like everyone else? Can he extinguish the existence of heaven?

Sorry for the lack of structure. Not all of these questions need to be answered, but I'm hoping NotReady and the other informed believers can clarify these things for me.
-ZJ