The words “so that” introduce a purpose clause. The reason for Satan’s arrest and imprisonment is “so that he might not deceive the nations any longer.” The implication is that up until the time of Satan’s arrest he had been able to deceive the nations. In fact, deception gets to the heart of Satan’s identity (John 8:44). Though defeated and turfed from heaven (Revelation 12:8–9), Satan remains in denial of Christ’s supremacy.
3 and threw him into the pit, and shut it and sealed it over him, so that he might not deceive the nations any longer, until the thousand years were ended. After that he must be released for a little while.