I don't understand the concept of God being omnipotent. If he was, then he'd know what he was going to do before he even did it. He stands above time and all other dimensions, so he would have known about his existence before he even existed. In order to make plans and decisions, you need to act over time. Which would mean that God has no free will, since everything was already predetermined. He can't be omnipotent if he doesn't have free will.
And then for the rest of us, it means we don't have a free will either. Our decisions aren't up to us, since God already knows what we're going to do and when we're going to do it. If I had a free will, God wouldn't know what I was doing tomorrow and therefore wouldn't be omnipotent.
Which then in turn leaves prayers obsolete, why would one pray for something when God already knows that person will make that prayer?
Sorry if that was confusing or didn't make sense.
On the first paragraph: God does stand above time, beyond time as we see it, which is subjectively.
On this:
"In order to make plans and decisions, you need to act over time. Which would mean that God has no free will, since everything was already predetermined."
No. God is outside of time entirely. Consider it like we live on a table in a box with the top cut off. He stands outside of the box entirely.
We are as a tree, all of creation. God is the gardener. We see things from the perspective of a growing tree. He is outside the tree entirely.
While this concept may be hard to imagine, consider ants: do ants know of your existence? Can they understand you? While we are made in the image of God, this does not mean our ways are His ways. His ways are higher then our ways as the Heavens are the earth.
As for our free will: free will is illusionary. It is a paradox. You do have freedom of choice. On the otherhand God does know everything you will do.
And He designed you that way.
So, you kind of don't have free will. If you are slave to sin, you do not have freedom but are bound to that which is the bad you do not wish to do. If you are a slave to righteousness then you are truly free.
Such a slave - one to righteousness - is free to do as they will, for their will is good.
They are then sons and daughters, no longer bondservants.
Simply believing the words of Jesus sets you truly free.
Now, the confusion you have here is quite simple: you are confusing "doing" with "being". This is what the world does, and many religions (including many Christians, unforunately). Freedom is about being, deeds come naturally from your being. Those who are good have good deeds come from them, those who are bad have bad deeds come from them.
Bad people trust in their own deeds, good people trust in deeds which come from God living in their hearts through the Spirit of God, which is the Spirit of Jesus Christ.
People want to judge words and deeds, and they get very caught up in that. Salvation is about being in a place of peace, love, and joy -- in quiet rest, however.
The slavery of those without free will is that their hearts are not at rest, they do not have goodness in them: no true joy.
Freedom, therefore, is more about being in a good place, wherever you are and whatever you do. Your home is always with you.
Slavery is about being imprisoned in a bad place, wherever you are and whatever you do.