what did thomas tell the others a the gathering

He told them that the Maze cant be solved. The creators throw variables at them, to weed them out to see who gives up.

The maze is a test. It cant be solved.

The Maze is a test. The Creators are throwing Variables at them and they're trying to determine whether the group of 50 boys in the Glade will give up or fight their way out. Turns out, half the group decided to come out of the maze with Thomas, Minho, and Newt. Alby died before they could escape. Wayyyyyy before they could escape.