The most important thing that one acquires through reading such basic Orthodox literature as this is a virtue which is called “discernment”
When we come to two phenomena which seem to be exactly alike or very similar to each other, the virtue of discernment allows us to see which of them is true and which is false:
that is, which has the spirit of Christ and which might have the spirit of Antichrist.
The very nature of Antichrist, who is to be the last great world ruler and the last great opponent of Christ, is to be anti-Christ—
The very nature of Antichrist, who is to be the last great world ruler and the last great opponent of Christ, is to be anti-Christ—
and "anti" means not merely "against," but also "in imitation of, in place of." The Antichrist, as all the Holy Fathers say in their writings about him, is to be someone who imitates Christ, that is, tires to fool people by looking as though he is Christ come back to earth.
Therefore, if one has a very vague notion of Christianity or reads the Scriptures purely from one's own opinions (and one's opinions come from the air, and the air is not Christian now, but anti-Christian), then one will come to very anti-Christian conclusions.
Seeing the figure of Antichrist, one will be fooled into thinking that it is Christ.
http://www.orthodoxphotos.com/readings/seraphim/signs/discernment.shtml
http://www.orthodoxphotos.com/readings/seraphim/signs/discernment.shtml