The katechon (from Greek: τὸ κατέχον, "that which withholds", or ὁ κατέχων, "the one who withholds") is a biblical concept which has subsequently developed into a notion of political philosophy.
The term is found in 2Thessalonians 2:6-7 in an eschatological context: Christians must not behave as if the Day of the Lord would happen tomorrow, since the Son of Perdition (the Antichrist of 1 and 2 John ) must be revealed before. Paul then adds that the revelation of the Antichrist is conditional upon the removal of "something/someone that restrains him" and prevents him being fully manifested. Verse 6 uses the neuter gender, τὸ κατέχον; and verse 7 the masculine, ὁ κατέχων.
The interpretation of this passage has raised many problems, since Paul does not speak clearly.
The following identifications of the katechon have been proposed: