Oh my goodness, what a question! The paradox here is that so much is being hidden we can’t even recognize what it is that is being concealed!
But we have to start somewhere so let’s start with a clue from the world of literature. Every epic saga contains a protagonist and an antagonist. The antagonist, who is clever, deceitful, manipulative, and enticing is typically engaged in battle against the protagonist. After many failed attempts at directly assaulting the protagonist, the antagonist will modify his methods. If he can’t hurt the protagonist, then he will hurt those who the protagonist loves.
Well, my dear readers, this is the point at which we can begin our investigation in exposing what is being hidden. For the book that exposes this epic saga is the Bible. In the Bible the epic battle between good and evil or God, the protagonist, and Satan, the antagonist, is disclosed. Stands to reason then Satan’s first plan of attack would be to conceal the truths of Scripture. Why?
The further removed humanity is from God and His plans for them, the more room Satan has to work. By being unaware of the Truth revealed in the Bible, mankind will discard the existence of God. Therefore, when belief in God is discarded, who’s going to believe in the existence of Satan?
Deception and manipulation are his primary tools to destroy individuals and thus in turn hurt God. For mankind is not Satan’s main target. God is! He hurts God by hiding the Truth from individuals and making them unaware of what is Truth.
So what about those who have been somewhat exposed to the Truths in the Bible? What is Satan’s line of attack with them? Keep them confused about who God, Jesus, Jesus’s death on the cross to pay for our sins, and the Holy Spirit is. All is hidden, if Satan can distance us from God’s word.
So what does Satan want to hide from those of us who are believers?
Well, mainly the Truth contained in the Bible. For the more familiar we are with God’s Truth, the less likely Satan will be able to hide Truth. And as believers, who have had the Truth unveiled, we understand that the more time we spend in God’s word and in prayer, the stronger we will become. We will gain insight into what is a lie and what is Truth. We will know the Truth and Satan’s attempts to hide it from us will utterly fail.