To get the most from God, remember it is not necessary to actually believe in the actual existence of God.
All you have to do is imagine the time when Abraham conceived of an omnipotent, eternal and moral God.
And then imagine how it would be if He existed.
And then imagine how it would be if He were your very own personal God.
It was the imagination of a mere man that conjured Him into existence, to assist him in his politics, morality and spirituality.
The question is not whether God exists, but whether YOU wish to enlist Him to be YOUR friend, when you already know you cannot trust anyone.
Therefore even if you do not really believe God exists, you could still have a relationship with Him and bargain with Him, if you know what you are supposed to do that just might help you get yourself into His good books to preserve you and aid your enterprises in this life only, if you do not believe in an afterlife.
Even if He does not really exist it is therapeutic, comforting and allows you to function independently of any other prop. Whatever works.
If God is only a spiritual and an emotional prop, He is at least more transportable and at hand than even your iPhone and Facebook account. You only have to think of Him to summon Him to your assistance and make Him listen to your concerns and anxieties, while you may lose your phone and have your Facebook account disabled.
Imaginary companions are an integral part of many children's lives. They provide comfort in times of stress, companionship when they're lonely, someone to boss around when they feel powerless, and someone to blame for the broken lamp in the living room. Most important, an imaginary companion is a tool young children use to help them make sense of the adult world.
God is just the adult version of this.