I prefer the following stanza of that poem “The Rubaiyat” and understand why theists don’t.
“And that inverted Bowl they call the Sky,
Whereunder crawling cooped we live and die,
Lift not your hands to It for help–for It
As impotently moves as you or I.”
It was for lines like this Omar has been considered a closet atheist or agnostic.
“Myself when young did eagerly frequent
Doctor and Saint, and heard great Argument
About it and about: but evermore
Came out by the same Door as in I went.”
And this from the same poem as the other examples, suggests that Omar might have had a lusty fondness for the company of agreeable women and the practice of imbibing alcohol and eating…hardly your pious muslim.
“A Book of Verses underneath the Bough,
A Jug of Wine, a Loaf of Bread–and Thou
Beside me singing in the Wilderness–
Oh, Wilderness were Paradise enow!”
And any complaints about copy should be directed to Edward FitzGerald who translated Khayyam’s works from the Farsi to English, unfortunately Mr FitzGerald died in 1883 but greater literary minds and run of the mill poetry lovers have declared his work a superlative translation which has never been out of print.