They say to the seers, "Do not see," and to the prophets," Do not prophesy the truth to us. Tell us flattering things. Prophesy illusions."
-Isaiah 30:10 (HCSB)

An illusion is a false idea or belief.  A delusion is a self-deception, a fool's paradise, misconception, or misapprehension.

We might have illusions about life.  When we accept the reality that the illusions are not true, we can become disillusioned.  Disillusionment is when we are angry or bitter or cynical about life.

God is neither under an illusion nor disillusioned about things.

Disillusionment carries with it the feeling of disappointment.  God can be disappointed, but not disillusioned, because God never was under any illusion.

Children are not born with wisdom about how the world works and how to function here.  Children grow in wisdom and understanding.  We expect children to be childish.  We expect children to live under some illusion.

The great task of life is to grow up, to become an adult. 

As life goes on, we grow in wisdom and understanding.  We are not in an illusion or disillusioned, but see life in reality.

Joni Mitchell's song, "Both Sides Now", expresses the idea, that after experiencing adult life, we can still choose the illusion over reality:
I've looked at life from both sides now
From win and lose and still somehow
It's life's illusions I recall
I really don't know life at all
The sad state, reflected in her words, is like that of a "fools paradise", or of a person who chooses to wear "rose colored glasses".  Why?  Perhaps because the illusions  keep the pain away.

There is a person, who has had life experiences, in time, but has chosen not to assimilate them into wisdom and maturity, but has chosen the path of illusion.

What is tricky with a Christian is that we are supposed to be hopeful.  Dreamers are hopeful and hopeful people might be accused of being "overly optimistic", looking at things unrealistically, or having "rose colored glasses on".

But, being hopeful and being in denial are different.  The hopeful one does not deny reality and does see it.  Hopeful people deal with hard realities, and find a way, if there is a way; and they know when to go a different way.

To walk with God is to be hopeful and optimistic, while embracing life's deep sorrows and joys.

Reinhold Niebuhr, wrote about something called, "A flight towards nothingness, where the primary concern is to escape the painful daylight of human consciousness."(1)  People who stay in illusions are trying to avoid (painful) reality.  They want to be unconscious to it.

Addictive behavior in the sensual realm is used to avoid reality.  Sensuality is not just sexual.  Niebuhr wrote this in "Nature and Destiny of Man":
Whether drunkenness, gluttony, sexual license, love of luxury, or any inordinate devotion to a mutable good, sensuality is always: (1) an extension of self-love to the point where it defeats its own ends; (2) an effort to escape the prison house of self by finding a god in a process or person outside the self; and (3) finally an effort to escape from the confusion which sin has created into some form of subconscious existence.(2)
The "sensual man" or woman is failing to trust God, as the bedrock of their life.  If you do not trust God, you put your trust in something or someone else.

When we rely on solutions, be they addictions, fantasies, or will-power; that are not an act of faith that expresses trust in God, we end up in pride, rather than humility.  And that is the life of embracing illusion, rather than reality.

Reality involves painful truth and grace.

Perhaps the worst aspect of the person's life who in living in illusions, is that they bring God into them.  They bring God into their fantasy world of denial, foolishness, and rebellion.  They engage in a "God is my co-pilot", or "The Man upstairs", skewed caricature of God, Jesus, and the Holy Spirit.

Reality is found in and through Christ.  Finding out that he loves you and you are his will change your life and bring you out of illusion and into reality.  I want to know what's real.  I want something real.  I want the real Jesus with no illusions.

Rows and flows of angel hair
And ice cream castles in the air 
And feather canyons everywhere 

I've looked at clouds that way 
But now they only block the sun 
They rain and snow on everyone 
So many things I would have done But clouds got in my way 

I've looked at clouds from both sides now 
From up and down, and still somehow 
It's cloud illusions 
I recall I really don't know clouds at all 

Moons and Junes and Ferris wheels 
The dizzy dancing way you feel 
As every fairy tale comes real 
I've looked at love that way 

But now it's just another show 
You leave 'em laughing when you go 
And if you care, don't let them know 
Don't give yourself away 

I've looked at love from both sides now 
From give and take, and still somehow 
It's love's illusions I recall I really don't know love at all 

Tears and fears and feeling proud 
To say "I love you" right out loud 
Dreams and schemes and circus crowds 
I've looked at life that way 

But now old friends are acting strange 
They shake their heads, they say I've changed 
Well something's lost, but something's gained In living every day 

I've looked at life from both sides now 
From win and lose and still somehow 
It's life's illusions I recall 
I really don't know life at all

I've looked at life from both sides now 
From up and down and still somehow 
It's life's illusions I recall 
I really don't know life at all