The anti-Christ is no secret.

For many deceivers have gone out into the world, those who do not confess the coming of Jesus Christ in the flesh. Such a one is the deceiver and the antichrist. 8 Watch yourselves, so that you may not lose what we have worked for, but may win a full reward. 9 Everyone who goes on ahead and does not abide in the teaching of Christ, does not have God. Whoever abides in the teaching has both the Father and the Son. 10 If anyone comes to you and does not bring this teaching, do not receive him into your house or give him any greeting, 11 for whoever greets him takes part in his wicked works.