God's sovereignty and human responsibility
1. God is sovereign. He created all, sustains all and rules over all. This is both assumed and explicitly stated at all times in Scripture. It also seems to be self evident - if God is God then he is supreme in everything ... or he isn't God, something else is.
2. Mankind is responsible for his actions. God holds man responsible for the decisions and actions we take. This is also ingrained into Scripture from the very first. It is both explicitly and implicitly taught throughout the Bible. When Adam sinned against God in the garden by eating the fruit God had said not to, God held him responsible. And God holding us responsible for our actions is the only reason the sacrifice of Jesus makes sense.
Both of these things are so ingrained into the story of the Bible that no-one seriously questions them - at least not directly.
But this immediately gets us into a dilemma. To paraphrase the Apostle Paul in Romans 9, if God is sovereign no-one can resist his will, so how can he still hold us responsible? If God decides to do something he does it and no-one can stop him. God decides, so we are helpless to disobey, therefore we are not really responsible. Therefore we can live as we like because we are not responsible for our actions. This view has been called hyper Calvinism (the name is libellous to John Calvin, but he can't do anything about it!), but is really a form of determinism.
This looks after the 'God is sovereign' stream of thought we find in the Bible. But it completely ignores the other stream that is also in the Bible, that people are responsible for their actions. Calvin certainly did not ignore human responsibility, but some who came after him did.
The other option we can have is to stress human responsibility. Man is responsible for his actions, therefore it follows that he is the one who makes the decisions. Man is a law unto himself. He is the one who decides how he will live and he is accountable to no-one ... but himself.
This certainly takes care of the 'human responsibility' theme in the Bible. But it completely ignores God's sovereignty. Man is sovereign; he makes the decisions. The upshot is, of course, that man effectively becomes God. At best God has to wait in the wings for man to decide what he wants to do. This is what historically is known as Arminianism.
So what do we do with these seemingly contradictory teachings of the Bible? It seems that this is a mystery beyond human comprehension. Not one limited to the Bible, by the way. Many cultures have grappled with this issue, and come up with many different explanations. They all go to one side or the other. As they must. But the Bible does not do that. It does not try to reconcile these two truths. It just assumes them and states them.
For us, here is the answer. Keep these two truths side by side without trying to reconcile them. Like two tracks on a railway line, they work well when they run together parallel, but when you try to get them to meet you have disaster on your hands. Our human, finite, sinful minds cannot grasp how these things can work.
Does that mean there is no answer to the mystery? That we will never understand? There is an answer, and someday it will be clear to us. I think the answer lies in the area of us being created in God's image. But how that works ... that is beyond my ability to grasp. But one day I will be in glory with Jesus, and all will be made clear.