There are a lot of things that will probably always be a mystery to me. If you care to know a few:
I don’t know how God makes a human being a whole thing. He made spiritual, mental, emotional, and physical aspects, but they’re all one piece! What happens to one of them affects the rest of them. And when the soul/spirit leaves the physical body, it dies. How do all these parts join or fit or weave together? How and why do they come apart? How do the soul and spirit affect the physical brain and the physical body? What are the implications when the physical brain begins to deteriorate but the soul/spirit is still there? Why and how do the aging, wounding, and sickness of the body bring you closer to the soul/spirit leaving it?
I don’t know how God is a Trinity, Father, Son, and Holy Spirit. I have a few metaphors to help me begin to grasp the concept, but I don’t fully understand. Then again, if I could fully understand God, He wouldn’t be much of a God, would He?
I don’t know how God weaves people’s life circumstances together, or how He weaves people’s lives together. He even does it multiple ways across the world and across human history! I know He does it to bring about goodness for His glory and our good, but the details are often astounding, and those are just the ones that I know! If you thought your favorite book or movie franchises were really meta and intricately woven together, just imagine how intricate God can get!
I don’t know what Heaven will be like. I know God will be there, I know there will be no impulse to sin, I know I will worship and praise, and I know a few things God has let us know in the Bible, but I don’t really know much else. Because God has made it and will be there, I know it will be good, the best thing anyone has ever known, but I don’t know in detail why and how. It’s a surprise for everyone. And then when I get to Heaven, will I still have questions about the things I do in this life? What will I already know and what will make sense once I finally see it there? What questions will even still matter?