Catechism of the Catholic Church on the tribulation, the great apostasy and the Antichrist:

Before Christ's SECOND COMING the Church must pass through a final trial that will shake the faith of many believers.

The persecution that accompanies her pilgrimage on earth will unveil the "mystery of iniquity" in the form of a religious deception offering men an apparent solution to their problems at the price of apostasy from the truth.

The supreme religious deception is that of the Antichrist, a pseudo- messianism by which man glorifies himself in place of God and of his Messiah come in the flesh.