Revelation Now :"I will strike her children dead. Then all the churches will know that I am he who searches hearts and minds, and I will repay each of you according to your deeds. Now I say to the rest of you in Thyatira, to you who do not hold to her teaching and have not learned Satan's so-called deep secrets (I will not impose any other burden on you): Only hold on to what you have until I come." (Revelation 2:23-25)
The deep secrets of Satan were either false teaching advocated by heretics, or secret insights by so-called believers "guaranteed" to promote deeper spiritual life. We should hold tightly to the basics of our Christian faith and view with caution and counsel any new teaching that turns us away from the Bible, the fellowship of our church, or our basic confession of faith. The so-called deep secrets of Satan are literally, the deep things of Satan - a scathing reference to the perverse teaching of the Nicolaitans. We cannot hide from Christ; he knows what is in our hearts and minds, and still he loves us. The sins we try to hide from God need to be confessed to him. Her children are those led astray into pagan immorality and worship. Their punishment is absolute.
"Searches hearts and minds" is translated in the Authorized Version as "searches the reigns and the hearts." "Reigns" are literally "kidneys", the seat of the emotions. Every emotion and thought is open to God's gaze. No one will deceive the Risen Christ. Satan's so-called deep secrets are known to the God who searches hearts and minds. God knows us, our thoughts, feelings and intentions.
Our God searches the innermost thoughts of our minds and the most tender feelings of our hearts.
"Search me, O God, and know my heart I pray, Try me O Lord and know my heart I pray,
See if there be some wicked thoughts in me, Cleanse me from every sin and set me free."