Today at work I thought of something that I recall as a quote,it goes as follows:If hell didn’t exist mankind would be obligated to create it.Can someone in the audiance tell me please who said that ,I realize the wording may differ from what I was thinking,but I am sure that someone else came up with that thought before I.
NadaHappyCamper 
I can think of a couple of similar phrases offhand…
From the movie The Usual Suspects:
“Verbal : Who is Keyser Soze? He is supposed to be Turkish. Some say his father was German. Nobody believed he was real. Nobody ever saw him or knew anybody that ever worked directly for him, but to hear Kobayashi tell it, anybody could have worked for Soze. You never knew. That was his power. The greatest trick the Devil ever pulled was convincing the world he didn’t exist.”
And from Voltaire:
“If God didn’t exist, it would be neccesary to invent him.”
Don’t need to post a cite for that, you can find a bazillion for yourself on google using a search string like “voltaire god exist”. Have a blast.
I suspect it’s the second quote you’re thinking of (it’s very famous), and you might be misremembering or combining two different quotes.
…and I DO know how to spell necessary. Grrr…
That’s what I think, too. I first became familiar with this idea reading The Brothers Karamazov, but in it, Dostoevsky quotes Voltaire: