There is a place for mystery in theology. God is bigger than us by such a magnitude that we cannot expect to understand everything about Him. He is beyond our comprehension.
But information does not have to come from reason, it can also come from education. Much of what you know was taught to you, in addition to what you figured out. When it comes to God, He wants us to know Him, and therefore He reveals Himself to us.
When it comes to understanding God, we can be too intrigued by mystery. It becomes a romantic concept. It also makes a great excuse for not studying deeper or working harder to understand God. But I think this love affair with mystery is a mistake. God delights in revealing Himself to us, and a wisdom is found by the one who delights in studying to know more.
Furthermore, being intrigued by mystery can be dangerous. From Gnosticism forward to the latest person claiming to be the second coming of Christ, the devil has used the idea of mysteries known only to a select few, to seduce humanity away from the true knowledge of God. Anytime you hear someone speaking of a secret of the ages that God has revealed only to them, beware.
So while mysteries do exist, our love affair with mysteries should be made to submit to a love for the things of God. Study God’s word and find the answers to His mysteries there.