This question is extremely important. Some people ponder the question of God without any guidelines and that can be problematic. Human beings tend to question everything including God, because we are taught to ponder and think about every aspect in our lives. However, when it comes to God, we simply cannot fully comprehend Him. The Ahlul-Bayt (as) tell us, when we try to understand God that, in fact, there are limits to what our minds can comprehend. They tell us that no matter how hard we try, we will never fully understand Him.
More specifically, the Ahlul Bayt state that we are unable to understand the answers to questions such as “What is God?”, “Who is God?”, or “What is God’s reality?” and attempting to do so without Divine understanding is not possible. We are not able to fully comprehend who God is because we are finite beings attempting to understanding an Infinite being.
So what are we supposed to think about?
The Imams tell us that we should think about the creations of God in order to better understand Him. There are also Quranic verses and narrations of the Ahlul-Bayt that aid us in our understanding of God.
No matter how much you work to develop your intellect, you will never be able to fully and completely understand Him because you are limited in your type of existence. As a finite being, you can only ever know, or understand, a finite amount. God, however, is infinite and cannot be constrained or limited, even by thoughts. In this way, it is impossible for us to completely understand God.
If you have a big circle and a small circle, can you fit the big circle in the small circle? No, you cannot.
Here on Earth, the mind itself is a “small circle”, and cannot understand the “big circle” that is God.