Is Satan omniscient?

from the old testament

• Satan is a created being, meaning he is inherently limited. Ezekiel 28:12–17, which many conservative interpreters understand to describe Satan’s fall, states, “You were blameless in your ways from the day you were created, till unrighteousness was found in you” (Ezekiel 28:15). Being created implies that he cannot share divine qualities.
• Indeed, Solomon's prayer indicates that only God is omniscient: “You [God] only, know the hearts of all the children of mankind” (1 Kings 8:39b).
• Satan, as only a creature, must seek out knowledge. The book of Job shows that Satan was "going to and fro on the earth, and from walking up and down on it” (Job 1:7b) and became intent on tempting Job (Job 1:8).
• Being limited does not mean that Satan is simple-minded. In the story of the fall, Satan, depicted as a snake, is described as “more crafty than any other beast of the field that the LORD God had made” (Genesis 3:1). But being smart does not make him omniscient.

from the new testament

• Jesus, speaking about the end times, said, “concerning that day or that hour, no one knows, not even the angels in heaven, nor the Son, but only the Father” (Mark 13:32). Satan, as a fallen angel, doesn't know when the end times will happen, even though he may know that his time is short (Revelation 12:12).
• Satan did not understand Jesus' significance. Before Jesus came to earth, God’s saving plan was “things into which angels long to look” (1 Peter 1:12c), meaning angels longed to know and understand what God was doing.
• In 1 Corinthians 2:8, Paul made a statement that many interpret as referring to spiritual rulers: “None of the rulers of this age understood [the gospel], for if they had, they would not have crucified the Lord of glory.” Had Satan known that salvation came through Jesus’ death, he would have done everything in his power to stop it instead of facilitating it.
• Another passage that proves this is Satan's temptation of Jesus. In those temptations, Satan apparently didn’t fully comprehend who he was dealing with or the impossibility of his task. By tempting Jesus (i.e., Matthew 4:1–11), he believed he could find a weakness in the Son of God.
• All of this indicates that Satan, as a creature, learns as he goes, not inherently knowing everything. That said, he is a cunning adversary and not to be taken lightly. Peter said, “Your adversary the devil prowls around like a roaring lion, seeking someone to devour” (1 Peter 5:8), and Paul warned believers to put on their spiritual armor to withstand his attacks (Ephesians 6:10–20). We are therefore not to be “outwitted by Satan; for we are not ignorant of his designs” (2 Corinthians 2:11).

implications for today

The spiritual realm can fascinate us, particularly when it comes to demons and Satan. However, while it is a real realm, we are not called to fear it. Satan is simply another creature. Like all creatures, he is limited in power and abilities. Scripture doesn't indicate that he knows what you are thinking or planning to do. Because he’s limited, it’s also likely that his knowledge of world events is not happening in “real time.”

But Satan is not an idiot. He has been observing humans for thousands of years. He knows how to manipulate us as if he can read our minds. When he tempts us with our greatest weakness, it isn't because he can read our minds; it's because he has observed common temptations of humankind over the centuries and has observed us, too. He doesn't play fair. He will use every trick in the book to deceive people. Believers should treat him as he is: a cunning adversary who wants to see us dead (John 8:44; 1 Peter 5:8).

Despite his ferociousness, Scripture gives us all we need to overcome him. It doesn’t teach us to engage him (or any demon) in spiritual warfare but tells us to put on the armor of God (Ephesians 6:11). That is, we are to stand firm against his attacks by holding fast to Scripture. Just as Jesus withstood Satan's attacks by showing him he was wrong through Scripture, so also should we steep ourselves in Scripture. Then, whenever a temptation presents itself, we are ready to defend against it. We are not to fear Satan but trust that God is keeping him on a leash till his final judgment and that He is protecting us (Job 1:12).