Deuteronomy 29:29 "The secret things belong to the Lord our God; but the things that are revealed belong to us and our children for ever, that we may do all the words of this law."

God has His secrets, not because He does not want us to know Him, but because He waits until the time is right to reveal things to us. We are not always ready or able to hear and understand everything God has to say to us. Truth is revealed, and events happen in the Divine timeline, in "the fullness of time." Only God knows when that is. All of salvation history is a process; God is leading humanity slowly but surely to its ultimate, wonderful, destination, the beginning of our new life with Him. The Israelites were not ready for everything God told Moses until they had been freed from Egypt and were being made ready for life in the Promised Land. And then, wow, did God reveal a lot to Moses! These books of the Old Testament are where we get so much of our understanding of God and His laws, because that was the time God chose to reveal them to humanity.

The things that have been revealed to us are much greater than what was revealed to Moses. We have Jesus Christ, the ultimate revelation, God Himself become man. We have His words to ponder and live by, and His actions to imitate and learn from. But Jesus said to his disciples at one point that He had much more to tell them, but they were not ready for it yet, they were to await the Holy Spirit who would reveal all things in time. (John 16:12-14). The Holy Spirit continues to work in and through all those who believe, and continues to reveal things to us in the fullness of time.

Humanity is constantly maturing, growing, and expanding its capacity for understanding. At the same time, the "timeline" of Salvation History keeps progressing, with God revealing things to us that are necessary for our times. The faithful continue to sometimes be given direct private revelation, such as at Fatima and Medjugorje; and continue to think and write, building on the thinking of and revelations to our predecessors. Divine Mercy was revealed to Saint Faustina in the 20th century. Look at the richness of that revelation which humanity did not have until it this humble Polish nun came along! Likewise, I believe the revelations to Luisa Piccarreta of the coming Kingdom of the Divine Will are meant to prepare humanity for the next step in God's plan. They still remain hidden in large part, but word is spreading. More and more people are learning what it means to live in the Divine Will, thus calling down the kingdom that is hovering above us, waiting to be revealed in "the fullness of time." 

So God has secrets, but only because His plan plays out over time. He will reveal all we need to know when the time is right. He will give all of us, past, present, and future, everything we need to enter His kingdom, just as He gave the Jews everything they needed to enter the Promised Land.