What does 2 Thessalonians 2:7 mean?
Paul is clarifying certain aspects of end times (1 Thessalonians 1:10; 4:13–17; 5:1–11). This includes particular events which must happen before the beginning of the day of the Lord (2 Thessalonians 2:3–5).Paul introduces a "mystery" in this verse. It is the mystery of lawlessness, and Paul says it is already operating. The New Testament word "mystery" identifies a truth previously hidden but later revealed. For example, Paul describes the union of saved Jews and saved Gentiles in the church as a mystery (Ephesians 3:1–6). Also, in 1 Corinthians 15:51 he refers to the resurrection of believers at the rapture as a mystery. Here, in 2 Thessalonians 2:7, he describes lawlessness as a "mystery" that is already at work. Lawlessness is present now, but it will culminate in the deeds of the man of lawlessness. This truth was hidden until God revealed it through Paul.
Currently, the restrainer holds back lawlessness, but he will be removed someday. When he is out of the way, lawless activities will culminate through the man of lawlessness. But who is the restrainer? Only the Holy Spirit has the power to hold back sin from becoming full blown. He does this through His convicting ministry. Jesus taught that the Holy Spirit would convict the world of sin and righteousness and judgment (John 16:8). He will do so through Jesus' followers, but at the rapture Jesus' followers will be removed from the earth, and the earthly influence of Holy Spirit, who dwells in us, will be greatly diminished. While the Holy Spirit will still be on the earth, His unique sin-restraining ministry through saved believers will be gone: He will no longer convict the world of sin through believers. Therefore, lawlessness will reach an unprecedented manifestation.
Verses 6 and 7 combine to make a powerful point about the evil we face during our earthly lives. Despite what some might think, God does not merely observe and do nothing, while suffering and death run rampant. This passage reminds us that God is restraining evil, even now.