"Predestination" for me is like a well thought of plan or design. Like you plan for a family vacation and imagine all the enjoyment you and your family will have. You planned for the places to visit, the transporation, the hotels, the food, resorts, and of course set aside the funding. You even provided for alternative plans in case something fouls up along the way -- some contingency plans. However good the plan  might be, you are not in control of how your family will feel and react. They may or may not appreciate the plan or parts of it. In other words, no matter how good your intention is and how good and intricate your design/plan is, you will not not be in control of the outcome. Why? -- because each member of your family have their own free will.

In the same way, God has a very good plan for the whole of mankind and for each person. And each has a free will to do whatever he wills. God also provided some basic guidelines that can allow us to experience the good life He planned for us. You can call these guidelines as "commandments" or rules of life, or even unversal truths. Some we discover by ourselves. Some we read from the writings or teachings of others who might have stumbled on the truth of God. And God in His goodness, to help us be guided along the way, revealed Himself to us (just to make sure we that we get it correctly)-- these are the things we read in the bible and wisdom handed down through tradition.