1, you should always believe in light, because there is light in your heart to become light.
2, you should always believe in light, because if you don't believe in light, there will be darkness!
3. You should always believe in light and always believe in its existence.
4. You should always believe in light, emit your own light, but don't blow out other people's light.
The complete statement is: "Do you believe in the existence of light?" , from Diga Altman.
In Diga Altman, Diga represents light and monsters represent darkness. Altman appeared to protect the world and defend peace.
In the play, Altman is people's belief. At last, people all over the world turned into light and defeated the monster, so there was the stalk of "Altman and Light".
The extension of "you should always believe in the light" means that no matter how dark it is, you should believe that the light is about to appear in your heart, so that you will not be defeated by the darkness. Not because you believe that light can be changed into light, but because there is light in your heart.