In the same way that a seed no larger than the tip of a needle brings forth hundreds of thousands of fruits, so Hazrat Mahdi (pbuh), just one man, will lead the whole world to happiness
The sublime attributes of Almighty Allah are without end. Allah creates the greatest from the weakest. He creates a whole human being from a tiny sperm. A fig seed the size of the tip of a needle turns into a fig tree many meters high. This brings forth hundreds of thousands of fruits. The tree is boundless. You put a seed, which is only the size of the tip of a needle in the ground; and if we could fast-forward the action, it would be a seed turning into a huge tree in just five minutes. Then it would rain down fruit; leaves and fruit just raining down, as if it wishes to cover Istanbul. Allah makes the seed a means to create truck-loads of fruit and make it rain down from the soil.
Hazrat Mahdi (pbuh) is only a servant of Allah, but Allah will make Islam reign across the world by means of Hazrat Mahdi (pbuh). Our Prophet (saas) reveals that he will first gather one person and then nine people around him. Then those nine people will become 30. There are various stages in the hadiths. Then they will be 313 people. They include people from around the whole world. That is the wisdom of Allah.
This is also in the Torah. Allah says in the Torah that he will make Islam reign across the world with just 11 people. Just 11 people with pure faith. This is highly significant, it shows how widespread the lack of faith is in the world. Allah says that he will make Islam reign across the world with just 11 people, ‘...if they truly believe.’ The Mahdi is the person who will introduce true faith to the world. So these 313 people are true believers. And through them, other people also come to believe and Islam then will reign, insha’Allah. (Adnan Oktar, A9 TV, January 17th, 2013)