Is this world an illusion?

Suppose you are hungry and you see stone, how do you feel? Do you feel anything about stone?
Suppose you are angry and you see same stone, how do you feel? You don't see that stone as stone, you see that as a weapon. The weapon you want to hit someone with.
Suppose the same stone is inside temple, at the main place where you worship. How do you feel? Worship? you will probably put tika on that stone also.
Suppose an animal enters temple and sees the same stone, will it mean something for that animal to worship? But will you argue with that animal if that animal thinks you are stupid to worship stone. No! but if person from other religion says same thing then conflict will arise!

The stone which has no significance at first sight rises to a level where you worship it! Do you know what is the difference? Our eyes see stone, and we know it is nothing more than stone but we perceive that stone differently according to our own emotions.

When great saints said "this whole world and existence is illusion(maya)", they may not mean all existence is illusion. They probably mean, the world we are perceiving is illusionary. When we can see the stone as just stone regardless of any emotion/situation then we become free from maya.

How will our life be if we are not free from maya?
We will not feel like praying or visiting temple when we are happy, we may go on saying god doesn't exist. We will feel proud of whatever we are doing but if we fall in great misery we will be back to praying. No matter whom you pray, you will at least pray.
This is the nature of maya. You see things the way it is necessary for your survival. You won't be able to understand how another sees this world and misery will continue. The whole world is a misery if you are not free from maya.

But once you are free from maya, you will see Happiness as happiness, not mine or your happiness; Love as just love, not as mine, your, others love; Religion as religion, not as mine or others; Temple as temple, not as mine, his or others. This is also called opening of third eye.The third eye does not mean someone’s forehead cracked and something came out! It simply means another dimension of perception has opened up and that dimension of perception sees things as it is. Because the third eye is the eye of vision. The two physical eyes are just sensory organs.