The power of the coming man of lawlessness is already at work in secret, similar to the antichrists in 1 John 2:18 (see 2 Thessalonians 2:3–6).
the mystery (Greek mustērion): This term is often used for ceremonies in mystery religions (see 2 Thessalonians 2:6).
at work: This suggests a spiritual intervention, whether divine or evil (1 Thessalonians 2:13; 2 Thessalonians 2:9; Ephesians 2:2).
the one who now restrains: This might be someone opposing the man of lawlessness, someone possessed by a demon (evil angel), or Satan, the one who possesses (2 Thessalonians 2:9; see study note on 2:6).