In the future, humanity is being threaten by some mysterious creatures called Angels, and the only way to stop them is by using giant mechas called Evangelions.
This anime is known for having a lot of symbols and secrets combined with religious references, but Evangelion is more than that.
Hideaki Anno; creator of the anime, was suffering from depression during the time he was making the series. You can see all his suffering and feelings embodied in the main character.
The 26 episodes are a complete therapy for all the psychological troubles that the characters are having, and the last two episodes are the conclusion of this. Evangelion is an anime about feelings, a story of how people make things to be accepted by others but all the pain that this could provoke, but what for me, what makes Evangelion great is its final message, a message not all series, books, movies, or even people can tell you this way: