Two things happen when theists IMAGE God.
Let's use the word image instead of the word imagine, and let us for the moment not argue God's existence and just worry about how God is conceived to be: imaged. Even atheists have a stake in this.
On the one hand, theists image God as wholly different from humanity by using words that are simply negations of what humans are. God is:
Im-material--not made of matter, like us. Im-mortal--not susceptible to mortality, like us. In-finite--not finite and limited, like us. Im-malleable--not susceptible to change, like us. Omni-scient--not restricted in knowledge, like us. Omni-potent--not constrained in power, like us. Omni-benevolent--not tainted with badness, like us. Omni-present--not confined in space, like us.
On the other hand, even while in the act of portraying God as wholly different from humans using the above negative attributes, theists simultaneously render God into human likeness, using a palette of human traits and painting God with human qualities.
Love and kindness decorate the image of God, yes, but meanness, pettiness, and violence are on the palette too.
God's 'human' attributions always erupt from the personalities of the people doing the imaging of God so that a personal rendering of God is a reliable sketch of the personality doing the imaging.
Ponder a given theist's image of God and you'll see a replica of that theist. If you are a theist, the God you have in mind, the image of God that you hold, is a mirror held up to yourself.
A kind man will image a Kind God. And a Kind God announces a man given to kindly acts.
A loving woman will image a Loving God. And a Loving God announces a woman disposed to acts of love.
A compassionate woman will image a Compassionate God. And a Compassionate God announces a woman inclining towards compassion.
A calm man will image a Calm God. And a Calm God announces a man prone to serenity.
(Why has there never been an image of a Funny and Witty God?)
A mean man will image a Mean God. And a Mean God announces a man inclined to meanness.
A petty woman will image a Petty God. And a Petty God announces a woman liable to pettiness.
A violent man will image a Violent God. And a Violent God announces a man tending towards violence.
And so it goes--to the last syllable of divine attribution: any image of God is created in the image of humanity.
(It might need to be said that an image of God need not accurately describe the real God, not even in sacred texts--texts that may embalm an ancient erroneous image of God as everlasting truth.)
An image of God has power to come back upon the image-maker as an agent of real-world activity. An image of God, portrayed with a specific human trait, will burnish and amplify that very trait in a person.
Here is the principle: Religion burnishes and amplifies what is already there inside someone.
We see this every day of the world:
A kind woman's kindliness is polished and enhanced by her personal image of her Kind God. But a petty woman buffs her pettiness to high sheen with the clenched chamois of her imaged Petty God.
And, woe to all of us, a violent man adds luster to his violent urges and becomes more violent with his image of a Violent God.
Who will rid us of this troublesome Violent Deity?
We would all hope to uproot a Violent God from the global scene (although he has an ancient pedigree and has never been entirely out of sight in any historic epoch).
Clear-headed Jewish, Christian, Islamic, Sikh, and Baha'i, Caodai, and Hindu theologians, and lay men and women in those religions CAN help unweave the efficient causes of a Violent God, and there's one absolutely necessary operation whereby they may diminish the image of a Violent God in young theists. (Older violent theists may be too far gone.)
Theologians and theists--in all theistic traditions--can offer a remedial theology that insists upon benign images of God and alerts the faithful to the human tendency to image God in their own likeness, even to the point of attributing human imperfections to God.
Remember, for hope's sake: A Violent God's genesis cannot be traced to supra-historical sources. A Violent God is an effect of conditions that create the Violent God's human creators. A Violent God is a figment of the imagination of dis-integrated personalities. A Violent God is as farfetched, fabulous and fantastic as the Phoenix. A Violent God does not bear resemblance to any real God that might exist. A Violent God is a mere idea and is not intractable or insusceptible to challenge.