Why can’t you describe God?

I haven’t seen them for awhile and when I have seen them I haven’t stopped in to look at what was being said. I know, I should have. Anyhow, here is the typical lead sentence on some atheist blogs. “How can Christians expect us to believe in God when they can’t even describe the God that they believe in?”

I don’t get it. What do atheists mean when they say we can’t describe the God that we believe in?

Aren’t these terms descriptions?

All Powerful,
All Knowing,
Eternal,
Omnipresent,
Merciful,
Slow to Anger,
A friend to the poor,
Full of Grace,
Patient,
Spirit,
Mind / Logos,
Triune: Father, Son and Spirit,
Source of objective morality,
Necessary,
Uncaused,
All-good,
Infinite,
Unique,
Compassionate
Lord of lords,
King of kings,
Creator,
Sustainer of the universe.
Independent of His creation,
Perfectly Holy,
Love,
Truth,
Righteous,
Sovereign,
Self-existent.
Elohim - The strong One, mighty Leader, supreme Deity.
Yahweh - Self-existent, changeless, Provider, Present,
Adonai - Majestic, Master, Owner.
True God,
Transcendent,
Saviour,
Supreme Lord.

I’m sure there are more descriptions than this. So what do atheists mean when they say we can’t describe the God in which we believe?